Group items tagged

“My first and biggest wish is that we had known early that Covid-19 was airborne,”

, “Once you’ve realized that, it informs an entirely different strategy for protection.” Masking, ventilation and air cleaning become key, as well as avoiding high-risk encounters with strangers, he says.

Instead of washing our produce and wearing hand-sewn cloth masks, we could have made sure to avoid superspreader events and worn more-effective N95 masks or their equivalent. “We could have made more of an effort to develop and distribute N95s to everyone,” says Dr. Volckens. “We could have had an Operation Warp Speed for masks.”

We didn’t realize how important clear, straight talk would be to maintaining public trust. If we had, we could have explained the biological nature of a virus and warned that Covid-19 would change in unpredictable ways.  

We didn’t know how difficult it would be to get the basic data needed to make good public-health and medical decisions. If we’d had the data, we could have more effectively allocated scarce resources

In the face of a pandemic, he says, the public needs an early basic and blunt lesson in virology

and mutates, and since we’ve never seen this particular virus before, we will need to take unprecedented actions and we will make mistakes, he says.

Since the public wasn’t prepared, “people weren’t able to pivot when the knowledge changed,”

By the time the vaccines became available, public trust had been eroded by myriad contradictory messages—about the usefulness of masks, the ways in which the virus could be spread, and whether the virus would have an end date.

, the absence of a single, trusted source of clear information meant that many people gave up on trying to stay current or dismissed the different points of advice as partisan and untrustworthy.

“The science is really important, but if you don’t get the trust and communication right, it can only take you so far,”

people didn’t know whether it was OK to visit elderly relatives or go to a dinner party.

Doctors didn’t know what medicines worked. Governors and mayors didn’t have the information they needed to know whether to require masks. School officials lacked the information needed to know whether it was safe to open schools.

Had we known that even a mild case of Covid-19 could result in long Covid and other serious chronic health problems, we might have calculated our own personal risk differently and taken more care.

just months before the outbreak of the pandemic, the Council of State and Territorial Epidemiologists released a white paper detailing the urgent need to modernize the nation’s public-health system still reliant on manual data collection methods—paper records, phone calls, spreadsheets and faxes.

While the U.K. and Israel were collecting and disseminating Covid case data promptly, in the U.S. the CDC couldn’t. It didn’t have a centralized health-data collection system like those countries did, but rather relied on voluntary reporting by underfunded state and local public-health systems and hospitals.

doctors and scientists say they had to depend on information from Israel, the U.K. and South Africa to understand the nature of new variants and the effectiveness of treatments and vaccines. They relied heavily on private data collection efforts such as a dashboard at Johns Hopkins University’s Coronavirus Resource Center that tallied cases, deaths and vaccine rates globally.

For much of the pandemic, doctors, epidemiologists, and state and local governments had no way to find out in real time how many people were contracting Covid-19, getting hospitalized and dying

To solve the data problem, Dr. Ranney says, we need to build a public-health system that can collect and disseminate data and acts like an electrical grid. The power company sees a storm coming and lines up repair crews.

If we’d known how damaging lockdowns would be to mental health, physical health and the economy, we could have taken a more strategic approach to closing businesses and keeping people at home.

t many doctors say they were crucial at the start of the pandemic to give doctors and hospitals a chance to figure out how to accommodate and treat the avalanche of very sick patients.

The measures reduced deaths, according to many studies—but at a steep cost.

The lockdowns didn’t have to be so harmful, some scientists say. They could have been more carefully tailored to protect the most vulnerable, such as those in nursing homes and retirement communities, and to minimize widespread disruption.

Lockdowns could, during Covid-19 surges, close places such as bars and restaurants where the virus is most likely to spread, while allowing other businesses to stay open with safety precautions like masking and ventilation in place.  

The key isn’t to have the lockdowns last a long time, but that they are deployed earlier,

If England’s March 23, 2020, lockdown had begun one week earlier, the measure would have nearly halved the estimated 48,600 deaths in the first wave of England’s pandemic

If the lockdown had begun a week later, deaths in the same period would have more than doubled

It is possible to avoid lockdowns altogether. Taiwan, South Korea and Hong Kong—all countries experienced at handling disease outbreaks such as SARS in 2003 and MERS—avoided lockdowns by widespread masking, tracking the spread of the virus through testing and contact tracing and quarantining infected individuals.

With good data, Dr. Ranney says, she could have better managed staffing and taken steps to alleviate the strain on doctors and nurses by arranging child care for them.

Early in the pandemic, public-health officials were clear: The people at increased risk for severe Covid-19 illness were older, immunocompromised, had chronic kidney disease, Type 2 diabetes or serious heart conditions

t had the unfortunate effect of giving a false sense of security to people who weren’t in those high-risk categories. Once case rates dropped, vaccines became available and fear of the virus wore off, many people let their guard down, ditching masks, spending time in crowded indoor places.

it has become clear that even people with mild cases of Covid-19 can develop long-term serious and debilitating diseases. Long Covid, whose symptoms include months of persistent fatigue, shortness of breath, muscle aches and brain fog, hasn’t been the virus’s only nasty surprise

In February 2022, a study found that, for at least a year, people who had Covid-19 had a substantially increased risk of heart disease—even people who were younger and had not been hospitalized

respiratory conditions.

Some scientists now suspect that Covid-19 might be capable of affecting nearly every organ system in the body. It may play a role in the activation of dormant viruses and latent autoimmune conditions people didn’t know they had

 A blood test, he says, would tell people if they are at higher risk of long Covid and whether they should have antivirals on hand to take right away should they contract Covid-19.

If the risks of long Covid had been known, would people have reacted differently, especially given the confusion over masks and lockdowns and variants? Perhaps. At the least, many people might not have assumed they were out of the woods just because they didn’t have any of the risk factors.

We are already seeing the first wave of "who won and who lost" sorts of stories pitting various governors' responses against each other in horse-race fashion, as if these were early polls for the 2024 presidential election.

Then reality stepped in. A surge of summer cases forced the imposition of some restrictions on Floridians, like local mask mandates imposed by mayors in some cities in South Florida.

Now DeSantis is claiming again to be a master of pandemic control, as Florida's beach-tourism-restaurant industry is said to be doing well. Never mind that the state's seven-day infection rate of 143.9 per 100,000 population places it 12th highest of the 50 states.

For example, as of March 22, over the last seven days, Florida has had the most Covid-19 cases in the country, according to data from the US Centers for Disease Control and Prevention (CDC), the 12th highest per capita case-rate, the fourth highest number of deaths, and the 17th highest death rate.

Once celebrated for his pandemic management, he is now getting poor marks on managing. He has not strutted or had roundtables of fan-doctors to sing his praise. But the fact is California's recent numbers are much better than those of Florida, coming in at about 47th in the country with a case-rate 46.8 per 100,000, according to the CDC's data, and fewer deaths as well.

Florida is ignoring the death toll and instead pushing the upbeat metrics the governor would like America to pay attention to: jobs are up! and schools are open! DeSantis stood up to the Covid-19 threat like John Wayne would have done!

Rather than wallow in reality, she chose to celebrate an active economy and the joys of hunting season (note: the South Dakota new-infection rate is climbing the charts once again and sits at 105 per 100,000 South Dakotans ).

These rate-the-governors perspectives ignore a basic fact: it is no time for trophies.

Worse, this obeisance to economic and social factors as measure of success creates a series of disturbing false equivalencies as they compare deaths against the economy.

Measuring Covid-19 management on anything other than the number of human lives lost is not only disgraceful, it will also almost certainly lead us to make all the wrong decisions once again and usher in yet another Covid-19 resurgence in the US.

But these latest shifts challenge key infection control assumptions that go back a century, putting a lot of what went wrong last year in context

They may also signal one of the most important advancements in public health during this pandemic.

If the importance of aerosol transmission had been accepted early, we would have been told from the beginning that it was much safer outdoors, where these small particles disperse more easily, as long as you avoid close, prolonged contact with others.

We would have tried to make sure indoor spaces were well ventilated, with air filtered as necessary.

Instead of blanket rules on gatherings, we would have targeted conditions that can produce superspreading events: people in poorly ventilated indoor spaces, especially if engaged over time in activities that increase aerosol production, like shouting and singing

We would have started using masks more quickly, and we would have paid more attention to their fit, too. And we would have been less obsessed with cleaning surfaces.

The implications of this were illustrated when I visited New York City in late April — my first trip there in more than a year.

A giant digital billboard greeted me at Times Square, with the message “Protecting yourself and others from Covid-19. Guidance from the World Health Organization.”

That billboard neglected the clearest epidemiological pattern of this pandemic: The vast majority of transmission has been indoors, sometimes beyond a range of three or even six feet. The superspreading events that play a major role in driving the pandemic occur overwhelmingly, if not exclusively, indoors.

The billboard had not a word about ventilation, nothing about opening windows or moving activities outdoors, where transmission has been rare and usually only during prolonged and close contact. (Ireland recently reported 0.1 percent of Covid-19 cases were traced to outdoor transmission.)

Mary-Louise McLaws, an epidemiologist at the University of New South Wales in Sydney, Australia, and a member of the W.H.O. committees that craft infection prevention and control guidance, wanted all this examined but knew the stakes made it harder to overcome the resistance. She told The Times last year, “If we started revisiting airflow, we would have to be prepared to change a lot of what we do.” She said it was a very good idea, but she added, “It will cause an enormous shudder through the infection control society.”

In contrast, if the aerosols had been considered a major form of transmission, in addition to distancing and masks, advice would have centered on ventilation and airflow, as well as time spent indoors. Small particles can accumulate in enclosed spaces, since they can remain suspended in the air and travel along air currents. This means that indoors, three or even six feet, while helpful, is not completely protective, especially over time.

To see this misunderstanding in action, look at what’s still happening throughout the world. In India, where hospitals have run out of supplemental oxygen and people are dying in the streets, money is being spent on fleets of drones to spray anti-coronavirus disinfectant in outdoor spaces. Parks, beaches and outdoor areas keep getting closed around the world. This year and last, organizers canceled outdoor events for the National Cherry Blossom Festival in Washington, D.C. Cambodian customs officials advised spraying disinfectant outside vehicles imported from India. The examples are many.

Meanwhile, many countries allowed their indoor workplaces to open but with inadequate aerosol protections. There was no attention to ventilation, installing air filters as necessary or even opening windows when possible, more to having people just distancing three or six feet, sometimes not requiring masks beyond that distance, or spending money on hard plastic barriers, which may be useless at best

clear evidence doesn’t easily overturn tradition or overcome entrenched feelings and egos. John Snow, often credited as the first scientific epidemiologist, showed that a contaminated well was responsible for a 1854 London cholera epidemic by removing the suspected pump’s handle and documenting how the cases plummeted afterward. Many other scientists and officials wouldn’t believe him for 12 years, when the link to a water source showed up again and became harder to deny.

Along the way to modern public health shaped largely by the fight over germs, a theory of transmission promoted by the influential public health figure Charles Chapin took hold

Dr. Chapin asserted in the early 1900s that respiratory diseases were most likely spread at close range by people touching bodily fluids or ejecting respiratory droplets, and did not allow for the possibility that such close-range infection could occur by inhaling small floating particles others emitted

He was also concerned that belief in airborne transmission, which he associated with miasma theories, would make people feel helpless and drop their guard against contact transmission. This was a mistake that would haunt infection control for the next century and more.

It was in this context in early 2020 that the W.H.O. and the C.D.C. asserted that SARS-CoV-2 was transmitted primarily via these heavier, short-range droplets, and provided guidance accordingly

Amid the growing evidence, in July, hundreds of scientists signed an open letter urging the public health agencies, especially the W.H.O., to address airborne transmission of the coronavirus.

Last October, the C.D.C. published updated guidance acknowledging airborne transmission, but as a secondary route under some circumstances, until it acknowledged airborne transmission as crucial on Friday. And the W.H.O. kept inching forward in its public statements, most recently a week ago.

Linsey Marr, a professor of engineering at Virginia Tech who made important contributions to our understanding of airborne virus transmission before the pandemic, pointed to two key scientific errors — rooted in a lot of history — that explain the resistance, and also opened a fascinating sociological window into how science can get it wrong and why.

Dr. Marr said that if you inhale a particle from the air, it’s an aerosol.

biomechanically, she said, nasal transmission faces obstacles, since nostrils point downward and the physics of particles that large makes it difficult for them to move up the nose. And in lab measurements, people emit far more of the easier-to-inhale aerosols than the droplets, she said, and even the smallest particles can be virus laden, sometimes more so than the larger ones, seemingly because of how and where they are produced in the respiratory tract.

Second, she said, proximity is conducive to transmission of aerosols as well because aerosols are more concentrated near the person emitting them. In a twist of history, modern scientists have been acting like those who equated stinky air with disease, by equating close contact, a measure of distance, only with the larger droplets, a mechanism of transmission, without examination.

Since aerosols also infect at close range, measures to prevent droplet transmission — masks and distancing — can help dampen transmission for airborne diseases as well. However, this oversight led medical people to circularly assume that if such measures worked at all, droplets must have played a big role in their transmission.

Another dynamic we’ve seen is something that is not unheard-of in the history of science: setting a higher standard of proof for theories that challenge conventional wisdom than for those that support it.

Another key problem is that, understandably, we find it harder to walk things back. It is easier to keep adding exceptions and justifications to a belief than to admit that a challenger has a better explanation.

The ancients believed that all celestial objects revolved around the earth in circular orbits. When it became clear that the observed behavior of the celestial objects did not fit this assumption, those astronomers produced ever-more-complex charts by adding epicycles — intersecting arcs and circles — to fit the heavens to their beliefs.

In a contemporary example of this attitude, the initial public health report on the Mount Vernon choir case said that it may have been caused by people “sitting close to one another, sharing snacks and stacking chairs at the end of the practice,” even though almost 90 percent of the people there developed symptoms of Covid-19

So much of what we have done throughout the pandemic — the excessive hygiene theater and the failure to integrate ventilation and filters into our basic advice — has greatly hampered our response.

Some of it, like the way we underused or even shut down outdoor space, isn’t that different from the 19th-century Londoners who flushed the source of their foul air into the Thames and made the cholera epidemic worse.

Righting this ship cannot be a quiet process — updating a web page here, saying the right thing there. The proclamations that we now know are wrong were so persistent and so loud for so long.

the progress we’ve made might lead to an overhaul in our understanding of many other transmissible respiratory diseases that take a terrible toll around the world each year and could easily cause other pandemics.

So big proclamations require probably even bigger proclamations to correct, or the information void, unnecessary fears and misinformation will persist, damaging the W.H.O. now and in the future.

I’ve seen our paper used in India to try to reason through aerosol transmission and the necessary mitigations. I’ve heard of people in India closing their windows after hearing that the virus is airborne, likely because they were not being told how to respond

The W.H.O. needs to address these fears and concerns, treating it as a matter of profound change, so other public health agencies and governments, as well as ordinary people, can better adjust.

It needs to begin a campaign proportional to the importance of all this, announcing, “We’ve learned more, and here’s what’s changed, and here’s how we can make sure everyone understands how important this is.” That’s what credible leadership looks like. Otherwise, if a web page is updated in the forest without the requisite fanfare, how will it matter?

Patients in this study had a mean age of 44 years, so were very much part of the young, working-age population. Only 18% had been hospitalised with COVID-19, meaning organ damage may occur even after a non-severe infection.

Another piece of early research (awaiting peer review) suggests that SARS-CoV-2 could also have a long-term impact on people’s organs.

Perhaps unsurprisingly, people with more severe disease initially – characterised by more than five symptoms – seem to be at increased risk of long COVID. Older age and being female also appear to be risk factors for having prolonged symptoms, as is having a higher body mass index.

Rather harder to explore is the symptom of fatigue. Another recent large-scale study has shown that this symptom is common after COVID-19 – occurring in more than half of cases – and appears unrelated to the severity of the early illness.

While men are at increased risk of severe infection, that women seem to be more affected by long COVID may reflect their different or changing hormone status.

Some symptoms of long COVID overlap with menopausal symptoms, and hormone replacement using medication may be one route to reducing the impact of symptoms.

What is clear, however, is that long-term symptoms after COVID-19 are common, and that research into the causes and treatments of long COVID will likely be needed long after the outbreak itself has subsided.

Amongst the male participants, the study found that COVID-19-related anxiety and stress was associated with greater desire for muscularity, with anxiety also associated with body fat dissatisfaction.

COVID-19, and the consequences of the restrictions introduced to help tackle it, could be contributing to a number of serious mental health issues.

In some cases, these issues can have very serious repercussions, including triggering eating disorders.

Certainly during the initial spring lockdown period, our screen time increased, meaning that we were more likely to be exposed to thin or athletic ideals through the media, while decreased physical activity may have heightened negative thoughts about weight or shape. At the same time, it is possible that the additional anxiety and stress caused by COVID-19 may have diminished the coping mechanisms we typically use to help manage negative thoughts.

uring lockdown, women may have felt under greater pressure to conform to traditionally feminine roles and norms

iven that masculinity typically emphasises the value of toughness, self-reliance, and the pursuit of status, COVID-19-related stress and anxiety may be leading men to place greater value on the importance of being muscular."

with 42 states reporting downward trends

Moderna says its vaccine protects against some variants

The good news, Fauci told CNN in a separate interview Monday, is that current Covid-19 vaccines are likely to be effective against the new variants.

Moderna said Monday its vaccine created antibodies that neutralized Covid-19 variants first found in the UK and South Africa

So far, about 19 million people -- nearly 6% of the US population -- have received at least the first dose of the Covid-19 vaccine, according to CDC data. More than 3.3 million are fully vaccinated.

100 million shots administered in the President's first 100 days in office.

Kentucky has used about 88% of their first doses

what it means to have been in “close contact”

cumulative

He wore a mask, but there were times during the day when he was with individuals who did not.

nd it will likely change how schools and offices handle positive cases. If, say, a child is exposed to a person with COVID-19 for five minutes at three points during the day, there may need to be considerations for quarantine

virus twice

his second round of illness was much more severe and required hospitalization.

it appears to be extremely rare as of now.

five months

Also, just because a person no longer has antibodies does not mean they’ve necessarily lost immunity

Researchers analyzed child care centers that stayed open throughout the pandemic and found that employees who watched those kids all day were not at any greater risk of contracting COVID-19 than they would have been otherwise.

wear a mask.

There just has not been a lot of data so far.

under the age of 6

Perhaps most importantly, day cares were generally very good about preventive measures, especially hand-washing and disinfecting frequently.

the virus may be associated with significant mental decline in some cases.

They found that some test-takers who had had COVID-19 had an “equivalent to the average 10-year decline in global performance between the ages of 20 to 70,” the researchers said.

Still, the new research provides clues about COVID-19′s long-term effects, and it’s certainly something experts will be paying attention to moving forward.

one of the leading modelers, Gabriela Gomes, suggested the entire area of research was being effectively blackballed out of fear it might encourage a relaxation of pandemic vigilance. “This is the very sad reason for the absence of more optimistic projections on the development of this pandemic in the scientific literature,” she wrote on Twitter. “Our analysis suggests that herd-immunity thresholds are being achieved despite strict social-distancing measures.”

Gomes suggested, herd immunity could happen with as little as one quarter of the population of a community exposed — or perhaps just 20 percent. “We just keep running the models, and it keeps coming back at less than 20 percent,” she told Hamblin. “It’s very striking.” Such findings, if they held up, would be very instructive, as Hamblin writes: “It would mean, for instance, that at 25 percent antibody prevalence, New York City could continue its careful reopening without fear of another major surge in cases.”

But for those hoping that 25 percent represents a true ceiling for pandemic spread in a given community, well, it almost certainly does not, considering that recent serological surveys have shown that perhaps 93 percent of the population of Iquitos, Peru, has contracted the disease; as have more than half of those living in Indian slums; and as many as 68 percent in particular neighborhoods of New York City

overshoot of that scale would seem unlikely if the “true” threshold were as low as 20 or 25 percent.

But, of course, that threshold may not be the same in all places, across all populations, and is surely affected, to some degree, by the social behavior taken to protect against the spread of the disease.

we probably err when we conceive of group immunity in simplistically binary terms. While herd immunity is a technical term referring to a particular threshold at which point the disease can no longer spread, some amount of community protection against that spread begins almost as soon as the first people are exposed, with each case reducing the number of unexposed and vulnerable potential cases in the community by one

you would not expect a disease to spread in a purely exponential way until the point of herd immunity, at which time the spread would suddenly stop. Instead, you would expect that growth to slow as more people in the community were exposed to the disease, with most of them emerging relatively quickly with some immune response. Add to that the effects of even modest, commonplace protections — intuitive social distancing, some amount of mask-wearing — and you could expect to get an infection curve that tapers off well shy of 60 percent exposure.

Looking at the data, we see that transmissions in many severely impacted states began to slow down in July, despite limited interventions. This is especially notable in states like Arizona, Florida, and Texas. While we believe that changes in human behavior and changes in policy (such as mask mandates and closing of bars/nightclubs) certainly contributed to the decrease in transmission, it seems unlikely that these were the primary drivers behind the decrease. We believe that many regions obtained a certain degree of temporary herd immunity after reaching 10-35 percent prevalence under the current conditions. We call this 10-35 percent threshold the effective herd immunity threshold.

Indeed, that is more or less what was recently found by Youyang Gu, to date the best modeler of pandemic spread in the U.S

he cautioned again that he did not mean to imply that the natural herd-immunity level was as low as 10 percent, or even 35 percent. Instead, he suggested it was a plateau determined in part by better collective understanding of the disease and what precautions to take

Gu estimates national prevalence as just below 20 percent (i.e., right in the middle of his range of effective herd immunity), it still counts, I think, as encouraging — even if people in hard-hit communities won’t truly breathe a sigh of relief until vaccines arrive.

If you can get real protection starting at 35 percent, it means that even a mediocre vaccine, administered much more haphazardly to a population with some meaningful share of vaccination skeptics, could still achieve community protection pretty quickly. And that is really significant — making both the total lack of national coordination on rollout and the likely “vaccine wars” much less consequential.

At least 20 percent of the public, and perhaps 50 percent, had some preexisting, cross-protective T-cell response to SARS-CoV-2, according to one much-discussed recent paper. An earlier paper had put the figure at between 40 and 60 percent. And a third had found an even higher prevalence: 81 percent.

The T-cell story is similarly encouraging in its big-picture implications without being necessarily paradigm-changing

These numbers suggest their own heterogeneity — that different populations, with different demographics, would likely exhibit different levels of cross-reactive T-cell immune response

The most optimistic interpretation of the data was given to me by Francois Balloux, a somewhat contrarian disease geneticist and the director of the University College of London’s Genetics Institute

According to him, a cross-reactive T-cell response wouldn’t prevent infection, but would probably mean a faster immune response, a shorter period of infection, and a “massively” reduced risk of severe illness — meaning, he guessed, that somewhere between a third and three-quarters of the population carried into the epidemic significant protection against its scariest outcomes

the distribution of this T-cell response could explain at least some, and perhaps quite a lot, of COVID-19’s age skew when it comes to disease severity and mortality, since the young are the most exposed to other coronaviruses, and the protection tapers as you get older and spend less time in environments, like schools, where these viruses spread so promiscuously.

Balloux told me he believed it was also possible that the heterogeneous distribution of T-cell protection also explains some amount of the apparent decline in disease severity over time within countries on different pandemic timelines — a phenomenon that is more conventionally attributed to infection spreading more among the young, better treatment, and more effective protection of the most vulnerable (especially the old).

Going back to Youyang Gu’s analysis, what he calls the “implied infection fatality rate” — essentially an estimated ratio based on his modeling of untested cases — has fallen for the country as a whole from about one percent in March to about 0.8 percent in mid-April, 0.6 percent in May, and down to about 0.25 percent today.

even as we have seemed to reach a second peak of coronavirus deaths, the rate of death from COVID-19 infection has continued to decline — total deaths have gone up, but much less than the number of cases

In other words, at the population level, the lethality of the disease in America has fallen by about three-quarters since its peak. This is, despite everything that is genuinely horrible about the pandemic and the American response to it, rather fantastic.

there may be some possible “mortality displacement,” whereby the most severe cases show up first, in the most susceptible people, leaving behind a relatively protected population whose experience overall would be more mild, and that T-cell response may play a significant role in determining that susceptibility.

That, again, is Balloux’s interpretation — the most expansive assessment of the T-cell data offered to me

The most conservative assessment came from Sarah Fortune, the chair of Harvard’s Department of Immunology

Fortune cautioned not to assume that cross-protection was playing a significant role in determining severity of illness in a given patient. Those with such a T-cell response, she told me, would likely see a faster onset of robust response, yes, but that may or may not yield a shorter period of infection and viral shedding

Most of the scientists, doctors, epidemiologists, and immunologists I spoke to fell between those two poles, suggesting the T-cell cross-immunity findings were significant without necessarily being determinative — that they may help explain some of the shape of pandemic spread through particular populations, but only some of the dynamics of that spread.

he told me he believed, in the absence of that data, that T-cell cross-immunity from exposure to previous coronaviruses “might explain different disease severity in different people,” and “could certainly be part of the explanation for the age skew, especially for why the very young fare so well.”

the headline finding was quite clear and explicitly stated: that preexisting T-cell response came primarily via the variety of T-cells called CD4 T-cells, and that this dynamic was consistent with the hypothesis that the mechanism was inherited from previous exposure to a few different “common cold” coronaviruses

“This potential preexisting cross-reactive T-cell immunity to SARS-CoV-2 has broad implications,” the authors wrote, “as it could explain aspects of differential COVID-19 clinical outcomes, influence epidemiological models of herd immunity, or affect the performance of COVID-19 candidate vaccines.”

“This is at present highly speculative,” they cautioned.

These devices can measure a person’s temperature, heart rate, level of activity and other biometrics. With this information, researchers have been able to track and detect COVID-19 infections even before people notice they have any symptoms.

Wearables can detect symptoms of COVID-19 or other illnesses before symptoms are noticeable. While they have proved to be capable of detecting sickness early, the symptoms wearables detect are not unique to COVID-19.

So a logical way to look for new drugs to treat a specific disease is to study individual genes and proteins that are directly affected by that disease.

But this idea of mapping the protein interactions of diseases to look for novel drug targets doesn’t apply just to the coronavirus. We have now used this approach on other pathogens as well as other diseases including cancer, neurodegenerative and psychiatric disorders.

An outbreak isn’t a double pendulum; it’s much more convoluted. Myriad chains of events, operating in overlapping networks, conspire to chart its course.

It’s the double pendulum, and as a physical object, it’s very simple: A pendulum (a string and a weight) is attached to the bottom of another. Its movement is explained by the laws of motion written by Isaac Newton hundreds of years ago.

But slight changes in the initial condition of the pendulum — say it starts its swing from a little higher up, or if the weight of the pendulum balls is a little heavier, or one of the pendulum arms is a bit longer than the other — lead to wildly different outcomes that are very hard to predict.

The double pendulum is chaotic because the motion of the first pendulum influences the motion of the second, which then influences the entire apparatus. There isn’t a simple scale or ratio to describe how the inputs relate to the outputs. A one-gram change to the weight of a pendulum ball can result in a very different swing pattern than a two-gram change.

It teaches us to understand the mechanics of a system — the science of how it works — without being able to precisely predict its future. It helps us visualize how something that seems like it should be linear and predictable just isn’t.

That’s why, when pressed, epidemiologists have to say they don’t know what’s going to happen.

Climate scientists clearly tell us adding CO2 to the air will increase global temperatures. Yet they argue about when the worst effects of climate change will be felt and how bad it will be

Still, they know the mechanics of outbreaks. The chaos “doesn’t necessarily mean we know nothing,” Kissler says. They understand the conditions that make an outbreak worse and the conditions that make it better.

There is a tough tension of the current moment that we all need to work through: The future is clouded in chaos, but we know the mechanics of this system

Here are the mechanics. Scientists know that if we let up on social distancing, without an alternative plan in place, the virus can infect more people. They know this virus is likely to persist for at least a few years without a vaccine. They know it’s very contagious. That it’s very deadly. They also know that its pandemic potential is hardly spent, and that most of the population of the United States and the world is still vulnerable to it.

Will residents keep up with mask-wearing and social distancing, even when their leaders relax regulations? Plus, there are scientific questions about the virus still not understood: Will it diminish transmission in a seasonal pattern? Do children contribute greatly to its spread? How long does immunity last after an infection? Why do some people breathe out more of the virus than others? The answers to these questions will influence the future, and we do not know the answers.

Scientists are still unraveling what makes the difference between a sprawling outbreak in one city and a more manageable one in another. Some of it is the result of policy, some is the result of demographics, some is about structural inequality and racism, and some comes down to individual behavior. Some of it is just luck. That’s chaos for you.

“I don’t see uncertainty as a lack of knowledge,” says Philipp Lorenz-Spreen, a physicist who studies the chaos of a different sort of viral dynamics. “I think it’s a fundamental part of how our world works. It’s not our fault we do not know where this all will go.”

Newton clearly told us what happens when an object drops from the sky. But follow his laws, and find that the path of a double pendulum is very, very difficult to predict.

There’s a simple mechanism that is helping me understand the many possible futures we face with the Covid-19 pandemic.

Epidemiologists are clearly telling us what happens when you bring masses of people together during a pandemic. But they can’t tell us the exact shape this outbreak will take.

Alaska became the first state to make vaccinations available to all adults over the age of 16 earlier this month, followed by Mississippi. Several others have since followed suit, including Arizona, Utah, Indiana, Georgia and West Virginia.

Other states are moving to make more groups eligible ahead of schedule, based on age or underlying conditions.

According to a map released by the White House COVID-19 Response Team on Friday, four states have yet to confirm plans to expand eligibility ahead of the May 1 deadline: New York, Wyoming, Arkansas and South Carolina, where officials have said they are not on track to hit that threshold until May 3.

Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, said at the briefing that the country has seen an uptick in case counts and hospital admissions, with the most recent 7-day averages showing about 57,000 cases and 4,700 hospitalizations per day, and hospitalizations hovering around 1,000.

The U.S. is administering 2.5 million shots a day at its current pace, Zients said, adding that vaccine makers are "setting and hitting targets." Some 27 million doses went to states, tribes and territories this week.

Johnson & Johnson has accelerated production of its single-shot vaccine and is on track to deliver 11 million doses next week.

“This virus has a surface protein that is primed to lock on that receptor and slip its RNA into the cell,”

Once inside, that RNA inserts itself into the cell’s own replication machinery and makes multiple copies of the virus. These burst out of the cell, and the infection spreads. Antibodies generated by the body’s immune system eventually target the virus and in most cases halt its progress.

“A Covid-19 infection is generally mild, and that really is the secret of the virus’s success,” adds Ball. “Many people don’t even notice they have got an infection and so go around their work, homes and supermarkets infecting others.”

the virus can cause severe problems. This happens when it moves down the respiratory tract and infects the lungs, which are even richer in cells with Ace-2 receptors. Many of these cells are destroyed, and lungs become congested with bits of broken cell. In these cases, patients will require treatment in intensive care.

Even worse, in some cases, a person’s immune system goes into overdrive, attracting cells to the lungs in order to attack the virus, resulting in inflammation

This process can run out of control, more immune cells pour in, and the inflammation gets worse. This is known as a cytokine storm.

Just why cytokine storms occur in some patients but not in the vast majority is unclear

Doctors examining patients recovering from a Covid-19 infection are finding fairly high levels of neutralising antibodies in their blood. These antibodies are made by the immune system, and they coat an invading virus at specific points, blocking its ability to break into cells.

Instead, most virologists believe that immunity against Covid-19 will last only a year or two. “That is in line with other coronaviruses that infect humans,

“It is clear that immune responses are being mounted against Covid-19 in infected people,” says virologist Mike Skinner of Imperial College London. “And the antibodies created by that response will provide protection against future infections – but we should note that it is unlikely this protection will be for life.”

“That means that even if most people do eventually become exposed to the virus, it is still likely to become endemic – which means we would see seasonal peaks of infection of this disease. We will have reached a steady state with regard to Covid-19.”

Skinner is doubtful. “We have got to consider this pandemic from the virus’s position,” he says. “It is spreading round the world very nicely. It is doing OK. Change brings it no benefit.”

In the end, it will be the development and roll-out of an effective vaccine that will free us from the threat of Covid-19,

the journal Nature reported that 78 vaccine projects had been launched round the globe – with a further 37 in development.

vaccines require large-scale safety and efficacy studies. Thousands of people would receive either the vaccine itself or a placebo to determine if the former were effective at preventing infection from the virus which they would have encountered naturally. That, inevitably, is a lengthy process.

some scientists have proposed a way to speed up the process – by deliberately exposing volunteers to the virus to determine a vaccine’s efficacy.

Volunteers would have to be young and healthy, he stresses: “Their health would also be closely monitored, and they would have access to intensive care and any available medicines.”

The result could be a vaccine that would save millions of lives by being ready for use in a much shorter time than one that went through standard phase three trials.

phase-three trials are still some way off, so we have time to consider the idea carefully.”

The agency cites the results of a study in Germany and clinical trials in the U.K. and Spain as supporting the safety of vaccine interchangeability.

As of late May, 50.6% of Canada's population had received at least one vaccination shot — but only 4.6% of the population was fully vaccinated.

"Different vaccine products have been used to complete a vaccine series for influenza, hepatitis A, and others to complete a vaccine series for influenza, hepatitis A, and others."

"Basically, all vaccines work by showing people's immune systems something that looks like an invading virus but really isn't. If the real virus ever comes along, their immune systems will recognize it and be prepared to fight it off.

"Using two different vaccines is a bit like giving the immune system two pictures of the virus, maybe one face-on and one in profile."

"Individuals who have received one dose of the Pfizer-BioNTech or Moderna COVID-19 vaccine should receive a second dose of the same vaccine to complete the vaccination series," the spokesperson added.

For many affected patients, brain function improves as they recover. But some are likely to face long-term disability,

The injuries resembled those from a series of tiny strokes occurring in many different areas of the brain,

Some patients also suffer brain damage when their lungs can no longer provide enough oxygen.

"What we found was that the very small blood vessels in the brain were leaking,"

To understand other, less obvious mechanisms, though, scientists needed brain tissue from patients with COVID-19 who died.

What's more, the inflammation and leaky blood vessels associated with all these symptoms may make a person's brain more vulnerable to another type of damage."We know that those are important in Alzheimer's disease and we're seeing them play a key role here in COVID-19,"

Researchers will assess patients' "behavior, their memory, their overall function" at six-month intervals, she says.

Dr. Byrne and her colleagues measured risky decision-making by presenting people with a gambling scenario. They could choose between two bets: One offered a guaranteed amount of money, while the other offered the possibility of a larger amount of money but also the possibility of receiving no cash. A different exercise measured people’s preference for immediate versus delayed rewards: Participants could choose a certain amount of money now, or a larger amount later.

Study subjects also reported Covid-19 precautions they had taken in their daily lives, including masking and social distancing.

with Covid-19, people don’t feel sick immediately after an exposure so the benefits of wearing a mask, social distancing or getting vaccinated aren’t immediately apparent. “You don’t see the lives you potentially save,” she says

“People generally are more motivated by immediate gratification or immediate benefits rather than long-term benefits, even when the long-term benefits are much greater,

Research has also found being extroverted or introverted affects how people make decisions about Covid-19 precautions. A recent study of more than 8,500 people in Japan published in the journal PLOS One in October 2020 found that those who scored high on a scale of extraversion were 7% less likely to wear masks in public and avoid large gatherings, among other precautions.

The study also found that people who scored high on a measure of conscientiousness—valuing hard work and achievement—were 31% more likely to follow Covid-19 public-health precautions.

Scientists believe that a person’s propensity to take risks is partly genetic and partly the result of early life experiences

Certain negative childhood experiences including physical, emotional or sexual abuse, parental divorce, or living with someone who was depressed or abused drugs or alcohol are linked to risky behavior in adulthood like smoking and drinking heavily, other research has found.

Studies of twins have generally found that about 30% of the difference in individual risk tolerance is genetic

And scientists have discovered that the brains of people who are more willing to take risks look different than those of people who are more cautious.

ambling task had differences in the structure and function of the amygdala, a part of the brain involved in detecting threats, and the prefrontal cortex, a region involved in executive

Even people who have the same information and a similar perception of the risks may make different decisions because of the ways they interpret the information. When public-health officials talk about breakthrough infections in vaccinated individuals being rare, for example, “rare means different things” to different people

“Please be assured that YOU ARE SAFE after vaccine from what matters — disease and spreading.”

The risks for vaccinated people are still not zero, because almost nothing in the real world is zero risk. A tiny percentage of people may have allergic reactions

the evidence so far suggests that the vaccines are akin to a cure.

The Moderna and Pfizer vaccines — the only two approved in the U.S. — are among the best vaccines ever created, with effectiveness rates of about 95 percent after two doses.

That’s on par with the vaccines for chickenpox and measles.

The Moderna and Pfizer vaccines are “essentially 100 percent effective against serious disease,” Dr. Paul Offit, the director of the Vaccine Education Center at Children’s Hospital of Philadelphia, said. “It’s ridiculously encouraging.”

“It’s going to save your life — that’s where the emphasis has to be right now,”

“We’re underselling the vaccine,”

Right now, public discussion of the vaccines is full of warnings about their limitations: They’re not 100 percent effective. Even vaccinated people may be able to spread the virus. And people shouldn’t change their behavior once they get their shots.

These warnings have a basis in truth, just as it’s true that masks are imperfect.

Between Aug. 1 and the Super Bowl in early February, the N.F.L. administered almost one million tests to players and staff.

Many other organizations have sought safety in mass testing.

When the coronavirus closed down the country last spring, many colleges and universities sought her advice on how to safely reopen.

Now, a new analysis suggests that schools, businesses and other organizations that want to keep themselves safe should think beyond strictly themselves.

By dedicating a substantial proportion of their tests to people in the surrounding community, institutions could reduce the number of Covid-19 cases among their members by as much as 25 percent, researchers report in a new paper, which has not yet been published in a scientific journal.

“It’s natural in an outbreak for people to become self-serving, self-focused,”

“If you’ve been in enough outbreaks you just understand that testing in a box doesn’t makes sense. These things are communicable, and they’re coming in from the community.”

“really profound implications, especially if others can replicate it,” said David O’Connor

“We want to start using more sophisticated modeling and probably economic theory to inform what an optimal testing program would look like.”

Dr. Sabeti is an epidemic veteran, part of teams that responded to an Ebola outbreak in West Africa in 2014 and a mumps outbreak in the Boston area a few years later.

The University of Illinois is testing its students, faculty and staff twice a week and has conducted more than 1.6 million tests since July.

At a time when testing resources were in short supply, many of these institutions were proposing intensive, expensive testing regimens focused entirely on their own members

‘You’re in a drought in a place with a lot of forest fires, and you have a shortage of fire alarms,’” she recalled. “‘And if you run out and buy every fire alarm and install it in your own house, you’ll be able to pick up a fire the moment it hits your house, but at that point it’s burning to the ground.’”

‘You’re in a drought in a place with a lot of forest fires, and you have a shortage of fire alarms,’” she recalled. “‘And if you run out and buy every fire alarm and install it in your own house, you’ll be able to pick up a fire the moment it hits your house, but at that point it’s burning to the ground.’”

Using real-world data from C.M.U., the researchers created a baseline scenario in which 1 percent of people at the school, and 6 percent of those in the surrounding county, were infected by the coronavirus, and the university was testing 12 percent of its members every day.

Under these conditions, the researchers found, if the university used all of its tests on its own members, it would have roughly 200 Covid-19 cases after 40 days

The researchers then tweaked the model’s parameters in various ways: What if the virus were more prevalent? What if students and staff did not report all their contacts? What if they were better about mask-wearing and social distancing? What if the university deployed more tests, or fewer?

Unsurprisingly, the more testing the university did, and the more information it had about its members’ close contacts, the fewer Covid-19 cases there were

But in virtually every scenario, sharing at least some tests with the broader community led to fewer cases than hoarding them.

Some universities are beginning to adopt this outlook.

“A virus does not respect geographic boundaries,” Dr. Pollock said. “It is ludicrous to think that you can get control of an acute infectious respiratory disease like Covid-19, in a city like Davis that hosts a very large university, without coordinated public health measures that connect both the university and the community.”

There are barriers to the more altruistic approach, including internal political pressure to use testing resources in house and concerns about legal liability.

the researchers hope that their model convinces at least some institutions to rethink their strategy, not only during this epidemic but also in future ones.

“An outbreak is an opportunity to buy a lot of community good will, or to burn a lot of community good will,” Dr. Sabeti said. “We could have spent an entire year building up that relationship between organizations and institutions and their communities. And we would have done all that hard work together, as opposed to everybody turning inward.”

Airlines and technology companies have been working on developing technology to do so, but New York's is the first pass being made widely available to residents.

The idea is similar to mobile airline boarding passes: they can be printed or stored on smartphones, and participating businesses and venues can use a companion app to confirm patrons' health status.

rather than boost the economy and encourage vaccination, efforts like the Excelsior Pass could wind up further spread of variants. It's also still not clear that vaccinated people cannot spread the virus to people who have not been vaccinated.

Some worry that the passes might encourage fraud and increase the spread of the virus by people who claim to be vaccinated or COVID-19 negative but aren't.

Some of the aggressive measures China took to control the epidemic – confining people to their homes, for example — have been described as "draconian" and a violation of civil rights, even if they ultimately proved effective.

According to Abraar Karan, a doctor at the Brigham and Women's Hospital and Harvard Medical School, the notion persists in global health that "the West is the best."

Some public health practitioners say the global health system is partially responsible for perpetuating these ideas.

According to a separate report by the Center for the Study of Hate and Extremism, anti-Asian hate crimes in 16 U.S. cities increased 149 percent in 2020, from 49 to 122.

"What you're seeing in the U.S. is this pre-existing, deep-seated bias [against Asians and Asian Americans] – or rather, racism – that is now surfacing," says D'Silva. "COVID-19 is just an excuse."

there's a sense among Western health workers that epidemics occur in impoverished contexts because the people there engage in primitive behaviors and just don't care as much about health.

"[Western health workers] come in with a bias that in San Francisco or Boston, we would never let [these crises] happen,"

doctors initially only considered a possible COVID-19 diagnosis among people who had recently flown back from China. That narrow focus caused the U.S. to misdiagnose patients who presented with what we now call classic COVID symptoms simply because they hadn't traveled from China.

In the case of COVID-19 and other outbreaks, Western countries often think of them as a national security issue, closing borders and blaming the countries where the disease was first reported. This approach encourages stigmatization, he says.

reframing the discussion to focus on global solidarity, which promotes the idea that we are all in this together.

the global health community – and Western society as a whole – has to discard its deep-rooted mindset of coloniality and tendency to scapegoat others

Instead of blaming Asians for the virus, blame the systems that weren't adequately prepared to respond to a pandemic.

The cognitive deficits were “of substantial effect size,“particularly among people who had been hospitalized with COVID-19, the researchers said, with the worst cases showing impacts “equivalent to the average 10-year decline in global performance between the ages of 20 to 70.”

the study’s findings could not be entirely reliable, since they did not compare before and after scores, and involved a large number of people who self-reported having had COVID-19, who had no positive test.