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The guilt I felt about this compelled me to objectively review the literature on mRNA vaccines. Not being an expert in virology or biochemistry, I realized I had to quickly master unfamiliar words like “transfection” and concepts about gene sequences. Slowly, the information I was devouring started changing my beliefs.

I learned that research into using mRNA for vaccinations and cancer therapies has been ongoing for the past 30 years. Trial and error have refined this modality so that it was almost fully fledged by the time Covid hit

The mRNA from the vaccine is broken down quickly in our cells, and the coronavirus spike protein is expressed only transiently on the cell surface.

Furthermore, this type of vaccine is harnessing a technique that viruses already use.

It was humbling to have to change my mind. As I booked my vaccination time slot, I realized how lucky I am to have access to all this research, as well as the training to understand it.

As medical professionals, we cannot afford to be paternalistic and trust that people will follow advice without all the facts. This is especially true in Australia, where the vast majority of us have never witnessed firsthand the ravages that this disease can inflict.

Like all new converts, I am now a true believer: I’d like everyone to be vaccinated. But autonomy is a precious tenet of a free society, and I’m glad the ethicists have advised against mandating the vaccine

just hope that with more robust discussion and the wider dissemination of scientific knowledge, we may sway people like me — who have what may be valid reservations — to get the vaccine.

He points out that if one HIV vaccine had succeeded, the company behind it would have won big. Instead, all of the competitors in the vaccine field learned from collective failure and contributed to collective wisdom. The many false starts of HIV vaccination sired an explosion of new technologies and helped usher in a possible new golden age of vaccines.

We can call our record-breaking vaccine-development process good luck. Or we can call it what it really is: a ringing endorsement for the essential role of science in the world.

As a parable of scientific progress, I sometimes imagine the life cycle of a tree. Basic scientific research plants a variety of seeds. Some of these seeds fail entirely; the research goes nowhere. Some seeds become tiny shrubs; the research doesn’t fail entirely, but it produces little of value

And some seeds blossom into towering trees with abundant fruit that scientists, companies, and technologists pluck and turn into the products that change our lives. For years, mRNA technology looked like a shrub. In 2020, it blossomed in full view.

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.

“Usually by four to six weeks, there’s not much left,” said Deepta Bhattacharya, an immunologist at the University of Arizona. But germinal centers stimulated by the mRNA vaccines are “still going, months into it, and not a lot of decline in most people.”

The broader the range and the longer these cells have to practice, the more likely they are to be able to thwart variants of the virus that may emerge.

“Everyone always focuses on the virus evolving — this is showing that the B cells are doing the same thing,” said Marion Pepper, an immunologist at the University of Washington in Seattle. “And it’s going to be protective against ongoing evolution of the virus, which is really encouraging.”

Dr. Ellebedy’s team found that 15 weeks after the first dose of vaccine, the germinal center was still highly active in all 14 of the participants, and that the number of memory cells that recognized the coronavirus had not declined.

“The fact that the reactions continued for almost four months after vaccination — that’s a very, very good sign,” Dr. Ellebedy said. Germinal centers typically peak one to two weeks after immunization, and then wane.

After an infection or a vaccination, a specialized structure called the germinal center forms in lymph nodes. This structure is an elite school of sorts for B cells — a boot camp where they become increasingly sophisticated and learn to recognize a diverse set of viral genetic sequences.

The results suggest that a vast majority of vaccinated people will be protected over the long term — at least, against the existing coronavirus variants

But older adults, people with weak immune systems and those who take drugs that suppress immunity may need boosters; people who survived Covid-19 and were later immunized may never need them at all.

In the absence of variants that sidestep immunity, in theory immunity could last a lifetime, experts said. But the virus is clearly evolving.

“Anything that would actually require a booster would be variant-based, not based on waning of immunity,” Dr. Bhattacharya said. “I just don’t see that happening.”

The good news: A booster vaccine will probably have the same effect as prior infection in immunized people, Dr. Ellebedy said. “If you give them another chance to engage, they will have a massive response,” he said, referring to memory B cells.

Dr. Ellebedy said the results also suggested that these signs of persistent immune reaction might be caused by mRNA vaccines alone, as opposed to those made by more traditional means, like Johnson & Johnson’s

But that is an unfair comparison, because the Johnson & Johnson vaccine is given as a single dose, Dr. Iwasaki said: “If the J & J had a booster, maybe it will induce this same kind of response.”

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.

Regulatory review and approval. If a medication or drug is proven safe and effective in clinical trials, the U.S. Food and Drug Administration gets involved to evaluate the vaccine and administer an approval. The International Federation of Pharmaceutical Manufacturers and Associations reports that, typically, 1 in 10 experimental vaccines make it all the way through regulatory approval.

Each one of those steps can take years, and a potential vaccine can get stalled indefinitely at any one of them.

There's not a whole lot that can be done to speed up the process and still arrive at a safe and effective vaccine. Currently, most medical and public health experts say we're at least 12 to 18 months away from having a usable vaccine against COVID-19.

Because of the lengthy timeline associated with vaccine development, nearly three dozen companies and academic institutions around the world are now directing resources towards the search

While these new approaches could speed a vaccine to market, it does raise some ethical questions about safety. It's also unclear just yet whether the rush will result in an effective vaccine faster

"In the beginning of the process, the research usually involves searching through tons of sources of data to uncover opportunities that may not be so obvious.

The trial will assess "safety and antibody production, meaning that testing various doses' safety and whether these doses are producing an immune response. This phase 1 trial is not studying the effectiveness of the vaccine in preventing coronavirus infection. That will come at a later phase of the research,

But the sense of urgency surrounding the need for a safe, effective vaccine to prevent COVID-19 is driving public health officials, private pharmaceutical companies and others to work as quickly as they can to find a solution. The sooner these vaccines and other medications can be tested, the sooner we might have a viable vaccine that can halt a global pandemic that shows few signs of slowing on its own. But right now, experts say that it will take at least a year and likely longer before such a vaccine is available

"At this point, the Oxford researchers have no idea whether they have something or not," Offit said. "You just get so tired of this 'science by press release.' "

There are currently 10 vaccines in human clinical trials worldwide, according to the World Health Organization. Four of the teams are in the United States: Moderna, Pfizer, Inovio and Novavax.

Moderna CEO Stéphane Bancel referred to the results as "positive interim Phase 1 data" and that "the Moderna team continues to focus on moving as fast as safely possible to start our pivotal Phase 3 study in July."

Moderna is collaborating on its vaccine development with the National Institute of Allergy and Infectious Diseases. Dr. Anthony Fauci, the director of NIAID, said while Moderna's numbers were limited, "it was good news" and he was "cautiously optimistic" about the vaccine.

Inovio and Moderna have said they expect their large-scale clinical trials, known as Phase 3 trials, to last around six months. Pfizer hasn't given a timetable for its Phase 3 trial.

"I've not seen anyone wrap up a Phase 3 trial in a month to six weeks," said Dr. Saad Omer, a Yale University infectious disease expert who's done clinical trials on polio, pertussis and influenza vaccines. "We need to benchmark this against realistic expectations."

"As vaccine researchers like to say, mice lie and monkeys exaggerate," Offit said.

One big stumbling block for any vaccine trial is that Covid-19 infection rates in many areas of the world are flattening out or declining.

The Oxford vaccine uses what's called an adenovirus vector. Adenoviruses cause the common cold, but in this case, the adenoviruses are weakened and modified to deliver genetic material that codes for a protein from the novel coronavirus. The body then produces that protein and, ideally, develops an immune response to it.

"Compared to previous vaccines, this method is more robust, more versatile, and yet, equally efficient," according to the blog, which notes that the Bill & Melinda Gates Foundation invested $53 million in a German biotech company that specializes in RNA vaccines.

Inovio's technology uses a brief electrical pulse to deliver plasmids, or small pieces of genetic information, into human cells. Inovio says those cells then produce the vaccine, which leads to an immune response.

On April 19, the BBC's Andrew Marr said he asked Gilbert "if it's guaranteed that a workable vaccine can actually be produced."

"Nobody can be absolutely sure it's possible. That's why we have to do trials. We have to find out. I think the prospects are very good, but it's clearly not completely certain,"

"It certainly worked in monkeys," Oxford's Hill told CNN's Burnett May 15. "That was quite an impressive impact and that was our first try, if you like, with a standard dose, a single dose of vaccine."

"I buy that this is a pandemic and we may need to show progress and show steps, and I'm OK with making forecasts if decision makers want that, but do it with a level of uncertainty, because that's what's warranted," said Omer, director of the Yale Institute for Global Health.

"Now researchers can't wait to step out to the microphone -- and there are so many microphones out there -- to say, 'I've got it! This looks really good!' " Offit said.