The day had started as one of triumph for Mr. Biden and his party, with Democrats coming off elections the day before that sealed control of the Senate by picking up two seats in Georgia and Congress scheduled to clear away the last formal Republican objections to his victory by certifying the Electoral College outcome.

Filling out his cabinet, Mr. Biden chose Judge Merrick B. Garland, whose Supreme Court nomination Republicans blocked in 2016, to be attorney general, placing the task of repairing a beleaguered Justice Department in the hands of a centrist judge.

The assault on the Capitol by pro-Trump demonstrators devolved into a physical confrontation that halted the process of certifying the Electoral College outcome

It’s not protest. It’s insurrection.

Other interest groups quickly seized on the Georgia results to ratchet up the pressure on Mr. Biden to make good on his campaign promises.

“The work of the moment and the work of the next four years must be the restoration of democracy, of decency, honor, respect, the rule of law,” he said, adding later: “We must step up

Mr. Biden’s advisers are deep into the process of developing policy proposals to deliver to Congress in the coming weeks, starting with another stimulus package

Shortly after, Mr. Trump posted on Twitter a one-minute video in which he empathized with the rioters because “we had an election that was stolen from us,” but then urged them to “go home now. We have to have peace. We have to have law and order.”

The Democratic victories in Georgia put Mr. Biden’s party in control at both ends of Pennsylvania Avenue and reduced the risk of total partisan gridlock in Congress, at least for two years.

“With Schumer in control of the calendar, he’s got the opportunity to do some really substantial things.”

The Biden team is also drafting proposals to implement the president-elect’s “Build Back Better” campaign agenda, including new government spending on clean energy, infrastructure, health care and education, financed by tax increases on the rich and corporations.

Mr. Biden’s allies in the Senate expressed optimism that, armed with committee chairmanships and control of the legislative calendar, they could advance the president-elect’s policy goals.

“We need to fix a lot of the damage Trump’s done, and then there’s pent-up demand for a whole lot of things — what do we do about climate and about racial inequality, about wealth inequality, about structural racism,” said Senator Sherrod Brown of Ohio, who is set to be the top Democrat on the Senate Banking Committee.

Mr. Biden has also proposed the most ambitious climate agenda of any president in history, including $2 trillion in spending on green initiatives. A majority in the Senate gives Mr. Biden options to make some of that happen.

But Mr. Biden’s agenda will be constrained by the Democrats’ narrow advantages in the House and in the Senate, where moderate Democrats such as Senator Joe Manchin III of West Virginia and Senator Kyrsten Sinema of Arizona will wield vast power over which plans can pass.

Before the outbreak of violence on Capitol Hill, Mr. Biden signaled on Wednesday morning that despite the shift of Senate control to Democrats, he would still attempt to build legislative coalitions with Republicans on his top priorities

A high-profile business lobbying group that has long supported many Republicans, the National Association of Manufacturers, denounced Mr. Trump on Wednesday for inciting the violence and suggested it was time for his administration to invoke a constitutional provision to remove him

There is commotion far down a hallway, and someone tells Mr. Evans that some people are trying to break into one of the chambers. He turns away and walks down the hall, shouting, “Oh my gosh, I can’t believe we’re in here right now! Who thought this was going to happen today?” He then tries to start a chant of “U.S.A.! U.S.A.! U.S.A.!” As the video ends several minutes later, he appears to be looking for an exit.

In a statement on Facebook on Wednesday evening, Mr. Evans said that he has “traveled across the country to film many different events,” and that earlier he had “had the opportunity to film at another event in DC.”

“I was simply there as an independent member of the media to film history.”

Roger Hanshaw, said in a statement on Wednesday night that he had “not spoken to Delegate Evans about today’s events,”

though he said he saw what was posted on social media. He added that “storming government buildings and participating in a violent intentional disruption of one of our nation’s most fundamental political institutions is a crime that should be prosecuted to the fullest extent of the law.”

Organizers were preparing for an expected crowd of 5,000 on Tuesday and more than 30,000 throughout the week, according to permits issued by the National Park Service.

In December, violent clashes in Washington between supporters of Mr. Trump and counterprotesters left four people with stab wounds. Preparing for similar brawls, the National Guard said on Monday it would dispatch about 340 troops to the rallies, responding to Ms. Bowser’s request for additional security.

“I hope the Democrats, and even more importantly, the weak and ineffective RINO section of the Republican Party, are looking at the thousands of people pouring into D.C. They won’t stand for a landslide election victory to be stolen,” Mr. Trump said, using the acronym for “Republican in Name Only.”

Yet despite Mr. Biden’s clear win, many of Mr. Trump’s allies were slated to speak at the protests this week and continue to promote the president’s false claims, including Roger J. Stone Jr. and George Papadopoulos, former Trump campaign advisers who recently received pardons.

Some of the speakers during the rally at the Freedom Plaza delivered aggressive speeches claiming the groups were “at war,” targeting Republicans in Congress who have refused to protest the results of the election.

Protesters have trickled to the Capitol since Monday, many without masks and crowded close together as they carried Trump flags and “Stop the Steal” banners.

Gov. Andrew M. Cuomo appeared to support Mayor Bill de Blasio in his desire to keep schools open, announcing on Monday that the state would not stick with its plan to close schools if the positivity rate hit 9 percent by the state’s metrics, and would instead leave the decision to local leaders.

But the teachers’ union quickly poured cold water on that plan by saying it wanted schools closed if the city hit the 9 percent state mark.

As the virus has spread in the broader New York City community — and a rapidly rising number of schools have been closed when two or more positive cases emerged in the building, and no link could be established between them — the Department of Education decided to change its quarantine policy.

The change is most likely intended to prevent the situation the city found itself in last month, when as many as 201 school buildings were closed for two weeks at one point. The students in the 103 schools that are temporarily closed are learning remotely.

One faction of the United Federation of Teachers called on the union and the city to immediately close all schools for in-person learning, rather than waiting to see if the numbers worsen. “Too many students, families and staff will become sick,” if schools remain open, U.F.T. Solidarity, a left-leaning caucus within the union, said in a recent statement.

in terms of when we’ll know who won, there’s a big difference between a race decided by two percentage points and one decided by 0.2 percentage points.

That means votes

cast before election day — more than three million, according to Gabriel Sterling, a top state election official — should already be compiled, and pretty much all officials will need to do Tuesday night is hit “tabulate.”

n an extremely tight race, results could be delayed several days while late-arriving ballots come in. The vast majority of Georgians have to get their ballots in by the time the polls close at 7 p.m.

Under Georgia law, a candidate can request one if the margin is less than half a percentage point.

Yet countries like South Africa are in a singular bind because they cannot hold out hope for charity. Although its government is nearly insolvent and half of its citizens live in poverty, South Africa is considered too rich to qualify for cut-rate vaccines from international aid organizations.

Poor and middle-income nations, largely unable to compete in the open market, rely on a complex vaccine sharing scheme called Covax.

A collaboration of international health organizations, Covax was designed to avoid the inequities of a free-market free-for-all.

y the middle of next year, South African officials hope to secure their first vaccine doses under Covax, even as they negotiate to buy supplemental supplies from drug manufacturers. But in a country where luxury estates are walled off from sprawling squatter villages, many expect the newest vaccines to remain a privilege for residents who can pay out of pocket or through supplemental insurance — a program that disproportionately benefits white people

The best chance that many South Africans have to get vaccinated anytime soon is to volunteer for a clinical trial and test unproven vaccines on their bodies. But that arrangement has raised ethical questions.

The people at the top, they’re going to get the vaccine, the people who have power,” said Mtshaba Mzwamadoda, 42, who lives in a one-bedroom corrugated metal shack with his wife and three children. “Maybe we’ll get the vaccine in 2025.”

In 2009, when the world feared a devastating H1N1 flu outbreak, rich countries hoarded the earliest vaccines. While the outbreak was far weaker than expected, it revealed the inequities that exist when countries compete for lifesaving medicine.

outh African medical advisers say the Covax system is incredibly important but also deeply frustrating. Governments must pay up front without knowing what vaccine they will receive or getting any guarantees on when the doses will arrive.

Many South Africans are deeply skeptical of pharmaceutical companies and wary of rampant government corruption

Outraged, health advocates have threatened to sue the country’s government to make the plans public.

Ultimately, though, money is the great differentiator. From the outset, South Africa’s government knew it could not afford to order doses before they were tested and approved, as wealthy countries did.

My assumption is that unless you get onto a vaccine study, you’re not going to have access to any vaccine anytime soon,” Dr. Gill said, “which is obviously quite heartbreaking.”

One example is the HPV vaccine, a drug that can prevent cervical cancer but is in short supply in South Africa. Supplies are so tight that the World Health Organization has recommended that wealthy countries temporarily stop expanding their vaccinating campaigns to cover boys, so other nations can focus at least on covering young girls.

Under contract with Johnson & Johnson, Aspen is expected to produce millions of vaccine doses. South African officials have high hopes for the vaccine, which does not need cold storage and promises to require one injection rather than two.

n poor and working-class townships, the greater fear is of a new lockdown. The government’s earlier aggressive lockdown devastated the economy and confined many people to tin shacks built an arm’s length apart, with a dozen families sharing an outhouse and many more sharing a water tap.

Indeed, doctors are reporting similar cases across the country and around the world. A small number of Covid patients who had never experienced mental health problems are developing severe psychotic symptoms weeks after contracting the coronavirus

Beyond individual reports, a British study of neurological or psychiatric complications in 153 patients hospitalized with Covid-19 found that 10 people had “new-onset psychosis.”

Although the coronavirus was initially thought primarily to cause respiratory distress, there is now ample evidence of many other symptoms, including neurological, cognitive and psychological effects, that could emerge even in patients who didn’t develop serious lung, heart or circulatory problems.

Medical experts say they expect that such extreme psychiatric dysfunction will affect only a small proportion of patients. But the cases are considered examples of another way the Covid-19 disease process can affect mental health and brain function.

Experts increasingly believe brain-related effects may be linked to the body’s immune system response to the coronavirus and possibly to vascular problems or surges of inflammation caused by the disease process.

Also striking is that most patients have been in their 30s, 40s and 50s. “It’s very rare for you to develop this type of psychosis in this age range,”

Some post-Covid patients who developed psychosis needed weeks of hospitalization in which doctors tried different medications before finding one that helped.

Persistent immune activation is also a leading explanation for brain fog and memory problems bedeviling many Covid survivors,

How long the psychosis lasted and patients’ response to treatment has varied. The woman in Britain — whose symptoms included paranoia about the color red and terror that nurses were devils who would harm her and a family member — took about 40 days to recover, according to a case report.

It found that nearly 75 percent of Americans are now wearing masks when they leave their homes.

What changed her mind?“The Biden administration, returning to listening to science and the fantastic stats associated with the vaccines,” she replied.

But the grim reality of the pandemic — with more than 200,000 new cases and some 3,000 deaths daily — and the wanness of this holiday season are perhaps among the biggest factors

A barrage of feel-good media coverage, including rapt attention given to leading scientists and politicians when they get jabbed and joyous scrums surrounding local health care workers who become the first to be vaccinated, has amplified the excitement, public opinion experts say.

The divide between women and men has become pronounced, with women being more hesitant. Black people remain the most skeptical racial group, although their acceptance is inching up: In September, a Pew Research poll said that only 32 percent of Black people were willing to get the vaccine, while the latest poll shows a rise to 42 percent. And though people of all political persuasions are warming to the vaccine, more Republicans than Democrats view the shot suspiciously.

A brighter indication, he said, is that two-thirds of the public say they are at least somewhat confident that a coronavirus vaccine will be distributed in a way that is fair, up from 52 percent in September.

The most pronounced pockets of resistance include rural residents and people between the ages of 30 and 4

Timothy H. Callaghan, a scholar at the Southwest Rural Health Research Center at Texas A&M School of Public Health, said that rural residents tend to be conservative and Republican, characteristics that also show up among the vaccine hesitant

. They also include immigrants and day laborers, many of whom do not have college degrees or even high school diplomas and so may be more dismissive of vaccine science.

The resistance also springs from their hampered access to health care in remote areas. In addition, the need to take off several hours of work from the inflexible demands of farming for travel and recovery from vaccine side effects makes the shots seem even less compelling, he added.

About 35 percent of adults between 30 and 49 over all expressed skepticism about the vaccine, according to the Kaiser poll. Dr. Scott C. Ratzan, whose vaccine surveys in New York with the City University of New York Graduate School of Public Health echo findings similar to the national polls, noted that this group doesn’t keep up on flu shots either. They are well out of the age range for routine vaccines.

Another group that has been uncertain about taking the vaccine is health care workers, who typically have high rates of acceptance for established vaccines.

But other hospitals say that staff time slots for the vaccine are becoming a hot commodity.

For months, Tina Kleinfeldt, a surgical recovery nurse at Long Island Jewish Medical Center, a hospital in the Northwell Health network, had absolutely no intention of getting the vaccine until long after the science and side effects had been established.

Then she realized that doses were still so scarce that she might not get another opportunity soon. So she said yes. She became the first nurse on her unit to get the shot.

Afterwards , she felt some muscle soreness at the site of injection. But she also felt elated, excited and relieved.

The Affordable Care Act provides additional protections, because it requires most health insurers to fully cover all federally recommended preventive care.

Some insurers, including Aetna and certain Blue Cross Blue Shield plans, have already announced that they will not bill patients for the vaccine or its administration.

The federal government has used other levers to curtail surprise vaccine bills. When it offered enhanced Medicaid payment rates this spring, it required states to fully cover coronavirus vaccines for all their enrollees as a condition of receipt. All 50 states accepted the extra funding, and are now subject to those

requirements.

That’s different from the rules around coronavirus treatment, which regulated insurers’ cost sharing but did not take steps to curtail billing by doctors and hospitals. That meant some patients received bills they didn’t expect.

What makes the vaccine protections unique is that there are requirements on both the insurers and the providers,”

Experts also worry about uninsured Americans. The United States does not have a national program to cover vaccination costs for them. For coronavirus, it is instructing health providers to submit costs associated with vaccination to a $175 billion Provider Relief Fund created last spring.

Additional fees could accompany a vaccine. Some providers are accustomed to charging a visit fee for all in-person patients. Most emergency rooms charge “facility fees,” the price of coming in the door and seeking care, as do some hospital-based doctors.

Federal law is quite clear that patients should not have to pay for the vaccine and its administration. But there isn’t language that defines what counts as “vaccine administration,” and whether the visit fee makes the cut.

The question that I’m still not clear on is what happens if someone walks into an outpatient department that charges a facility fee and gets a vaccine,” said Kao-Ping Chua, an assistant professor of pediatrics at the University of Michigan who has studied coronavirus medical billing. “Is there a possibility they could get charged? I think the answer is yes.”

And yet, that is the very same position that Black people — and other people of color, religious minorities and women — are often forced into, or are asked to assume.

We have to acknowledge that Trump is a racist — something proven over and over again by his own words and actions — and that he still received a record number of votes for a sitting president anyway.

We have to acknowledge that he bragged about sexually assaulting women, had scores of women accuse him of sexual misconduct and was revealed to have paid off at least two women for their silence about alleged affairs.

We have to acknowledge that he has disparaged Mexicans, Muslims, Haitians and African nations.

These things happened. These people who supported him mostly knew these things happened. In many cases they heard Trump say them live on television or tweet them from his Twitter account.

And yet, his supporters still supported him. Many of them still do, even after his refutation of democracy. Many believe Trump’s lie that he actually won the election that he lost

oe Biden, as he has always said, is seeking to be a unifying president, to be the president of the people who didn’t vote for him as well as the ones who did.

supply-chain attack

According to SolarWinds S.E.C. filings, the malware was on the software from March to June. The number of organizations that downloaded the corrupted update could be as many as 18,000, which includes most federal government unclassified networks and more than 425 Fortune 500 companies.

The magnitude of this ongoing attack is hard to overstate.

The Russians have had access to a considerable number of important and sensitive networks for six to nine months.

While the Russians did not have the time to gain complete control over every network they hacked, they most certainly did gain it over hundreds of them.

The logical conclusion is that we must act as if the Russian government has control of all the networks it has penetrated

The actual and perceived control of so many important networks could easily be used to undermine public and consumer trust in data, written communications and services.

hat should be done?On Dec. 13, the Cybersecurity and Infrastructure Security Agency, a division of the Department of Homeland Security — itself a victim — issued an emergency directive ordering federal civilian agencies to remove SolarWinds software from their networks.

It also is impractical. In 2017, the federal government was ordered to remove from its networks software from a Russian company, Kaspersky Lab, that was deemed too risky. It took over a year to get it off the networks.

The remediation effort alone will be staggering

Cyber threat hunters that are stealthier than the Russians must be unleashed on these networks to look for the hidden, persistent access controls.

The National Defense Authorization Act, which each year provides the Defense Department and other agencies the authority to perform its work, is caught up in partisan wrangling. Among other important provisions, the act would authorize the Department of Homeland Security to perform network hunting in federal networks.

The response must be broader than patching networks. While all indicators point to the Russian government, the United States, and ideally its allies, must publicly and formally attribute responsibility for these hacks. If it is Russia, President Trump must make it clear to Vladimir Putin that these actions are unacceptable. The U.S. military and intelligence community must be placed on increased alert; all elements of national power must be placed on the table.

President Trump is on the verge of leaving behind a federal government, and perhaps a large number of major industries, compromised by the Russian government. He must use whatever leverage he can muster to protect the United States and severely punish the Russians.President-elect Joe Biden must begin his planning to take charge of this crisis. He has to assume that communications about this matter are being read by Russia, and assume that any government data or email could be falsified.

I confess that by the end of the week, the tiniest shadow of doubt had invaded my own mind. And no wonder: The usual inference that even young children are able to draw from experience — “This has never happened before so it’s very unlikely to be happening now” — has proved of dubious utility.

Dana Nessel,

The court, she said, delivered “an important reminder that we are a nation of laws, and though some may bend to the desire of a single individual, the courts may not.”

t’s as if someone filed a case asking the court to exercise its original jurisdiction and declare the moon to be made of green cheese. We would hardly pat the justices on the back for tossing out such a case. More likely, we would shrug and say, “There goes another nut case.”

And celebrating the court for its restraint in the election cases may be premature. The 2020-21 term, nearly three months in, is still unfolding.

The one or two such cases the court decides in a typical year have a certain charm despite their obscurity.

n June, the justices took the somewhat surprising step of asking the Trump administration for the federal government’s view on the dispute.

Early this month, the Office of the Solicitor General filed the government’s brief, urging the court to accept the case and noting that “resolving such conflicts among sovereigns falls within the core of this court’s original and exclusive jurisdiction.” The court will probably announce early in the new year whether it will assume jurisdiction.

In July, Federal District Judge Theodore Chuang, who sits in Greenbelt, Md., issued an injunction requiring the agency to permit doctors, for the duration of the pandemic, to mail or deliver the medication. In October, the Supreme Court responded to the Trump administration’s request for a stay of the injunction by sending the case back to Judge Chuang, telling him to permit the government to argue among other points, that improvements in the Covid-19 situation since the spring meant that visiting a doctor’s office was no longer a sufficient obstacle to merit relaxing the rule for mifepristone.

“It is hope,” said Kenzie Frankl, a registered nurse and clinical care leader for Sanford Health in Fargo who volunteered nine months ago to work in the hospital’s coronavirus unit and walked out of the vaccination room with a Day-Glo bandage on her arm.

New coronavirus cases have receded recently in North Dakota — which had the country’s highest rate of infections earlier this fall. But the pandemic is worse than ever in Kansas, where Dr. Maggie Hagan took a break from her rounds in Wichita to get vaccinated.

Five units in her hospital have been turned into coronavirus wards. She sees 50 patients each day.“I almost could cry talking to you now,” she said. “I feel like I didn’t just get a vaccine, I got a shot of hope.

Then there is the personal toll of working 12-hour shift after 12-hour shift sheathed in protective gear, worried that while one patient is treated another may be deteriorating. Some worried about carrying the virus home while others were treated by friends or neighbors as if they had the plague. Some have experienced post-traumatic stress disorder. Many have spent hours after work agonizing over the challenges of treating coronavirus patients.

Ms. Hansen described the 5,000 frontline nurses of the Memorial Healthcare System as resilient but physically and mentally exhausted by the pandemic

Ms. Hansen said the vaccine brought a breath of relief after so much sickness, suffering and death.

Receiving the vaccine alleviates some of his fears, but he said he would continue to wear a mask and practice social distancing, just to be safe.

The lack of concrete options left him and his colleagues feeling demoralized about their ability to help their patients, who were some of the sickest they had ever seen. After long, desperate shifts, they sometimes talk on the phone about the challenge of treating such an aggressive and unknown illness.

Like many of the doctors and nurses who lined up on Monday, Yvonne Bieg-Cordova, a radiology manager at Christus St. Vincent in Santa Fe, N.M., has watched lots of people die. But nothing prepared her for Covid-19.

Ms. Bieg-Cordova received her first dose of the vaccine on Monday, a bright moment after a bleak year.

Ms. Bieg-Cordova said that the past couple months have been trying, but that the vaccine did provide the hope that an end was coming.

On Tuesday, the White House proposed its own $916 billion plan, which would include more than $400 billion for small businesses.

Many small businesses say they can’t wait that long. A survey from the National Federation of Independent Business on Tuesday showed optimism falling and uncertainty rising as the nationwide surge in coronavirus cases leads governments to reimpose restrictions and consumers to pare their spending.

If that happens, it could be a disaster for both state economies and state budgets. Local businesses are major sources of tax revenue — both directly and through their employees — and major drivers of economic activity. If they fail in large numbers, it will slow the economic recovery once the pandemic is over.

“Even though we didn’t have to shut down like the restaurants and bars and the travel industries, it didn’t matter,” he said. “The business wasn’t there.”

In recent weeks, his company, Modular Systems Technicians, received a $10,000 grant from a new state fund to help small businesses. He also got money under a program that refunded $8 billion from the state workers’ compensation fund.“It helped,” Mr. Meurer he said. “It’s not nearly enough, but they did what they could.”

As part of the $2.2 trillion CARES Act last spring, Congress created a $150 billion fund that states could tap in responding to the virus. They were given wide latitude in using the money — as long as they did so before the end of the year.

“If we don’t help them get through this, will it ever come back?” Mr. Polis asked. “Sure, but it means years of boarded-up stores and restaurants on Main Streets across America if Democrats and Republicans can’t come together now to act.”

Some states are trying creative ways to stretch resources. California last month established a “rebuilding fund,” which will use a comparatively small amount of public money to provide loan guarantees to encourage for-profit and nonprofit lenders to make low-interest loans to small businesses.

Ms. Tyson said the loans should help businesses make investments to adapt to life during the pandemic

“I’m not concerned about how hard I can work, how I can connect with my customers or my community,” Ms. Stein said. “I am concerned that I will eventually run out of money.”

Still, a growing number of studies highlight the value of social interaction to brain development. Research shows that neural networks influencing language development and broader cognitive ability get built through verbal and physical give-and-take — from the sharing of a ball to exchanges of sounds and simple phrases.

These interactions build “structure and connectivity in the brain,” said Kathryn Hirsh-Pasek, director of the Infant Language Laboratory at Temple University and a senior fellow at the Brookings Institution. “They seem to be brain feed.”

John Hagen, professor emeritus of psychology at the University of Michigan, said he would be more concerned about the effect of lockdowns on young children, “if this were to go on years and not months.”

Portland has proved a little less prohibitive place for childhood interaction in part because there is more space than in the dense neighborhoods of San Francisco, and so children can be in the same vicinity without the parents feeling they are at risk of infecting one another.

he rise of small neighborhood pods or of two or three families joining together in shared bubbles has helped to offset some parents’ worries. But new tough rules in some states, like California, have disrupted those efforts because playgrounds have been closed in the latest Covid surge and households have been warned against socializing outside their own families.

o that end, what infants, toddlers and other children growing up in the Covid era need most now is stable, nurturing and loving interaction with their parents, Dr. Volling said.

“These children are not lacking in social interaction,” she said, noting that they are getting “the most important” interaction from their parents.

t also means that Mr. Biden will most likely come into office as the Justice Department is actively investigating his son, a case his political opponents are certain to seize on to try to damage the early days of his presidency.

The investigation could also complicate Mr. Biden’s efforts to instill public confidence that the department can operate independent of the personal interests of the president after it became deeply politicized under President Trump. L

“It’s not my Justice Department. It’s the people’s Justice Department.”

Mr. Biden has long been an intense target of Mr. Trump and his allies over the range of business ventures he pursued around the world during his father’s time as vice president and beyond

Mr. Biden and a group of partners — including his uncle James Biden, the president-elect’s brother — were also involved in negotiations about a joint venture with a Chinese energy and finance company called CEFC China Energy in 2017, documents provided by a jilted former business partner show.

The Republican report, which was released weeks before Election Day in an apparent effort to damage the Biden campaign, found no evidence of improper influence or wrongdoing by the former vice president.

Efforts by Mr. Trump and his supporters to damage Mr. Biden’s presidential campaign took on new urgency in October after The New York Post published reports based on files from a laptop that appeared to have belonged to Hunter Biden. The Post, which obtained materials from Mr. Trump’s personal lawyer Rudolph W. Giuliani, reported that the laptop had been seized by the F.B.I.

The Biden team has rejected some of the claims made in the Post articles, but has not disputed the authenticity of the files upon which they were based.

Mr. Trump and his allies openly pressed the Justice Department to disclose negative information about Mr. Biden ahead of the election, but investigators did not make overt moves that would have exposed the investigation before the ballots were cast.

Being in close proximity to people I don’t know will always feel less safe than it used to,” said Ellicott Matthay, a postdoctoral scholar at the University of California, San Francisco.

Three-quarters of respondents said they planned to spend Christmas, Hanukkah or other winter holidays only with members of their household, or not celebrate at all, similar to how they spent Thanksgiving.

Most scientists say around 70 percent of the population will need to be immune for the United States to reach herd immunity, when the virus slows down significantly or stops.

Nearly a third of respondents said they would be comfortable returning to more activities of daily life once they were vaccinated.

Since the spring, 79 percent of the epidemiologists said their assessment of various risks had changed, and that they had adjusted their behaviors accordingly. Science is a process, they said, and the virus is new, so even those studying it most closely have learned things along the way.

“It entirely depends upon what we do as a nation to address the pandemic,” said Emeli Anderson, a doctoral student of epidemiology at Emory. “Right now, we are not nearly doing enough.”

Many epidemiologists expressed disappointment and frustration that public health messaging had not been more effective, and that a growing share of Americans seemed to distrust science.

“This virus has humbled me as a professional and a person,” said Michelle Odden, associate professor of epidemiology at Stanford. “I did not think this level of failure in a federal response was possible in the United States. We have a lot of work to do.”

As for the future, some said that parts of life could begin to return to normal sometime in the summer, thanks to vaccines. B

ut assuming a highly effective therapeutic drug isn’t developed, a significant number said it would be at least a year before they felt it would be safe to do many of the things they used to.

Many said they planned to keep working from home at least part of the time. Some said they would always be more hesitant about greeting people with a handshake or a hug, being in crowded places or traveling internationally.

Their concerns came to life Wednesday afternoon at a park in the upscale Atlanta suburb of Alpharetta, where hundreds of Trump supporters gathered, waving American flags and Trump flags, to cheer two lawyers who have challenged the Georgia election results in federal court, Sidney Powell and L. Lin Wood.

But in other ways, the momentum seemed to turn against Mr. Trump this week. On Tuesday, a top state election official, Gabriel Sterling, laced into the president, pleading with him to scale back the conspiratorial rhetoric that Mr. Sterling said was inspiring people to make violent threats against election workers.

Aside from trying to assuage Mr. Trump, Republicans in Georgia also appear to be laying the groundwork for new limits on voting, and particularly on absentee voting. Mr. Trump has baselessly claimed that there was something fraudulent about the signature-matching system election officials used to verify the identities of absentee voters.

The president may spout conspiracy theories and acrimony — he has publicly attacked Mr. Raffensperger and Mr. Kemp for not acceding to his wishes — but he is also the most popular figure in the Republican Party. Nationally, Mr. Trump’s sustained assault on voting integrity, while false, has persuaded many Republicans that there was something crooked about the election. And no one is sure whether, or for how long, he will continue to command the fealty of his party.

But the fact remains that Mr. Raffensperger and Mr. Kemp have refused to give Mr. Trump what he wants most: an opening that would allow the results to be overturned (Mr. Kemp has not only certified the state’s 16 electors; he has also refused to call a special session of the legislature, which people like Mr. Wood have demanded, and where the election results could ostensibly be overturned).

Noting that the U.S. attorney general, William P. Barr, had just said that the Justice Department found no widespread fraud in the national race, Mr. Raffensperger said, “Our investigators have seen no widespread fraud either.”

This week, Nse Ufot, chief executive of the New Georgia Project, said that Mr. Raffensperger was “resorting to desperate attempts to smear law-abiding organizations and scare eligible Georgians from registering to vote in critical upcoming elections.” Mr. Raffensperger’s office said on Wednesday that Ms. Ufot’s group had sent an absentee ballot registration form to his dead son.

“I would be highly surprised and very disappointed,” Mr. Chambliss, the former senator, said in an interview, “if Donald Trump came to Georgia this weekend and had any comments that weren’t positive about any Republican politician.”

“In the U.K., they’ve just been able to say, ‘We have the data, we’re having the meeting,’” said Stephen Evans, a professor of pharmacoepidemiology at the London School of Hygiene & Tropical Medicine.

To speed the process, Britain’s Medicines and Healthcare Products Regulatory Agency had its experts review vaccine data as it became available, and separate teams worked in parallel on different parts of the process, rather than one waiting for another to finish.

The countries that remain in the European Union are waiting for its regulator, the European Medicines Agency, to authorize a vaccine. Like the F.D.A., the European regulator has scheduled a Dec. 29 meeting to consult outside experts and offer an opinion on the Pfizer vaccine.

Pfizer plans to ship 800,000 doses to Britain in the coming days. Starting Tuesday night, those doses were being prepared for shipping at a factory in Puurs, Belgium, BioNTech said.

A government advisory body released its list of vaccine priority groups on Wednesday. At the top of the list are nursing home residents and workers, followed by people older than 80 and health and social care workers.

The British decision will not in itself bring vaccinations closer anywhere else. But Pfizer executives said on Wednesday that they had already heard from other countries that, in light of Britain’s go-ahead, were looking to accelerate their own approval processes.American regulators, despite months of pressure from Mr. Trump, have maintained that they will follow their plan and review Pfizer’s vaccine to the F.D.A.’s standards.

The United States has pre-ordered 100 million doses of the Pfizer vaccine.

Rudolph W. Giuliani, a lawyer for Mr. Trump who has been at the forefront of promoting his election conspiracy theories, said that his team had gathered evidence of illegal voting in six states, backed up by sworn witness statements, and that the Justice Department had failed to investigate what the team had uncovered. 

There’s been one assertion that would be systemic fraud, and that would be the claim that machines were programmed essentially to skew the election results. And the D.H.S. and D.O.J. have looked into that, and so far, we haven’t seen anything to substantiate that,” Mr. Barr said, referring to the Department of Homeland Security and his own department.

Mr. Barr had been mostly silent since the election, but some Republicans privately pushed him to publicly rebut Mr. Trump, according to a person told of those conversations. His comments may have been prompted by Mr. Trump’s increasingly specious election claims; the president suggested on Sunday that the Justice Department and the F.B.I. may have played a role in an election fraud.

Mr. Barr had given prosecutors the authority to examine allegations by Mr. Trump’s allies of voter ineligibility in Nevada and improperly dated mail-in ballots in Pennsylvania. The results of those investigations have not been publicly disclosed, but Mr. Barr’s remarks suggested that any impropriety was too insignificant to change the election results.

“Most claims of fraud are very particularized to a particular set of circumstances or actors or conduct. They are not systemic allegations, and those have been run down; they are being run down,” he said. “Some have been broad and potentially cover a few thousand votes. They have been followed up on.”

But none, at least so far, have won Mr. Trump anything more significant than the ability to move his poll observers from 10 feet to six feet away from workers counting votes in Pennsylvania.

The campaign and its allies have now lost nearly 40 cases across the country as judge after judge — including some appointed by Mr. Trump — discredited the efforts as lacking both legal merit and convincing proof.

In the months before the November election, Mr. Barr had been one of the loudest voices sounding alarms about widespread fraud, claiming repeatedly in speeches and interviews that the potential for it was high and that it posed a grave danger to the election. Mr. Barr’s claims were often false or exaggerated and were widely refuted.