Home / Health / We might need a booster shot for COVID-19, but when? and which one?

We might need a booster shot for COVID-19, but when? and which one?



Pharmacist prepares Pfizer COVID-19 vaccine  at a clinic in Nashville on May 13, 2021. (Brett Carlsen/The New York Times)

Pharmacist prepares Pfizer COVID-19 vaccine at a clinic in Nashville on May 13, 2021. (Brett Carlsen/The New York Times)

As the country approaches President Joe Biden’s goal of a 70% vaccination rate, many are beginning to wonder how long their protection will last.

For now, scientists are asking a lot of questions about COVID-19 stimulant injections. But still there is not much answer. The National Institutes of Health announced recently that it has begun a new clinical trial on people who have been fully vaccinated — with a licensed vaccine — to see if Moderna boosters will. Increase antibodies and prevent viral infection for longer?

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Although many scientists speculate that vaccines Licensed Pfizer-BioNTech, Moderna and Johnson & Johnson in the United States will last at least one year. but no one knows for sure It is unclear whether the new coronavirus will change our vaccination needs.

“We’re in unfamiliar waters in terms of stimulants,” said Dr Edward Belongia, a physician and public health researcher at the Marshfield Clinic Research Institute in Marshfield, Wisconsin.

Why do we have to get the flu vaccination every year, but two measles vaccines in childhood can protect us for life?

various pathogens It affects our immune system in different ways. For some diseases, such as measles, one illness prevents another infection for life. but for other pathogens Our immunity weakens over time.

on some important issues Vaccines mimic natural infections. that we don’t really have to get sick Measles vaccine provides lifelong immunity. Tetanus vaccine, on the other hand, creates protection that fades year after year. The Centers for Disease Control and Prevention recommends vaccination against tetanus once a year.

And sometimes the virus itself can change. This caused the need for supporters to create new, customizable defenses. The influenza virus can mutate so much that a new vaccine is required every year.

How does the COVID-19 vaccine compare to others in terms of protection?

The short answer is we’re not sure yet. This is because people started getting a lot of vaccinations a few months ago.

Dr. Kirsten Like, a vaccine specialist at the University of Maryland School of Medicine. And the lead of the NIH stimulation experiment said, “Even in the experiment, We don’t know what the immune response is like in a year.

But the initial signs were encouraging. Researchers took blood from volunteers in vaccine trials and measured the levels of antibodies and immune cells targeting the coronavirus. Levels are dropping, but it is likely with this slow decline. Vaccine protection will remain strong for a long time. People who have been infected and vaccinated may receive more durable protection.

“I think there is a real possibility that immunity can persist for many years compared to the original strain,” Belongia said.

If that possibility doesn’t happen, COVID-19 stimulants may not be needed for many years. But that’s a big deal if

Will some coronavirus vaccines last longer than others?

Maybe. Scientists have discovered that vaccines using different technologies have different efficacy. The strongest vaccines are Moderna and Pfizer-BioNTech. both of which are based on RNA molecules. Vaccines using inactivated viruses, such as those made by Sinopharm in China and Bharat Biotech in India, have proven to be less effective.

It’s not clear why this is the case, says Scott Hensley, an immunologist at the University of Pennsylvania. The RNA vaccine is relatively new. Therefore, the stimulated immunity has not been thoroughly studied. In his own research on mice vaccinated with different types of flu vaccine – some made from RNA and others inactive – Hensley saw similar differences. The levels of antibodies produced by both vaccines are “Very different,” he said.

It is possible that protection from the less effective COVID-19 vaccine will fade faster. Sinopharm’s vaccine may already be showing some signs of this decline. Clinical trials have indicated that it is 78% effective, but the United Arab Emirates and Bahrain have now offered an outstanding drug to people who have received the Sinopharm vaccine to boost their weakened immunity.

How do we know our vaccines are losing effectiveness?

Scientists are searching for biological markers that can reveal when protection from vaccines is no longer sufficient to suppress the coronavirus. It is possible that a certain level of antibody will hit the threshold: if your blood is measured above that level. show that you are in good shape But if you are below You are at increased risk of infection.

Some preliminary studies suggest that these marks also known as defense correlation. contained in the COVID-19 vaccine Research is underway to find them.

“That will teach us a lot,” said Dr. H. Clifford Lane, deputy director of clinical research and special programs at the National Institute of Allergy and Infectious Diseases.

What about the variables?

We may need a booster to block variables. But still not clear

The emergence of variables in recent months has accelerated research on boosters. Some species have mutations that cause them to spread rapidly. Some species have mutations that could blunt the efficacy of licensed vaccines, but at this point scientists still have little clue as to how existing vaccines work against the different strains.

For example, last month Researchers in Qatar publish results of a study on vaccines. Pfizer-BioNTech This was awarded to more than 250,000 residents of the country between December and March.

Clinical trials have shown the vaccine to be 95% effective compared to the original coronavirus, but a variant called alpha. which was first identified in the UK Reduced efficiency to 89.5%, the first identified variant in South Africa, known as beta. This reduced the efficacy of the vaccine to 75%. However, both vaccines are 100% effective in preventing serious, serious or even fatal disease.

Just because a variant can evade an existing vaccine doesn’t mean it becomes a widespread problem. For example, beta remains rare in countries with strong vaccine programs such as Israel, the UK and the US. If beta is still rare will not pose a serious threat

But evolution still has a lot of room to play with with the coronavirus. Scientists cannot rule out the possibility that new strains may emerge in the coming months that spread rapidly and resist vaccines.

Dr. Grace Lee, Deputy Chief Medical Officer for Innovative Practice and Infectious Disease Physician at Stanford Children’s Health, said: “It’s clear that variables are different. is inevitable “I think the question is How will they be affected?”

Do we need a special booster tailored to a particular model?

it is not clear Some scientists suspect that a high immune response to the original version of the coronavirus will protect against strains. is sufficient as well But it is also possible that vaccines designed to protect against one particular variant may be more effective.

Pfizer has started a trial run to test both options. Some volunteers who have already received 2 doses will receive the same dose a third time. As part of the same experiment Researchers will give support to other experiments. designed to protect against beta variants

“From what we have learned so far. Our current thinking is Until we see the turnover of SARS-CoV-2 and COVID-19 disease decrease, we think it is possible that a third vaccine will be added internally. After 12 months of vaccination, it may be necessary to help prevent COVID-19,” said Jericha Pitts, Pfizer’s director of global media relations.

Can I change the brand of vaccine when I get the booster?

Maybe. In fact, a lot of research into other diseases suggests that changing vaccines can be a booster. “This is a tried and true idea from pre-Covid,” Lyke said.

Lyke and her colleagues are testing a mix and match option for boosters as part of a new trial. They are recruiting fully vaccinated volunteers from three vaccines licensed in the United States — Johnson & Johnson, Moderna and Pfizer-BioNTech.

All volunteers were given Moderna support. The researchers then observed how strong the immune response was.

It is possible that other vaccines For example, Novavax and Sanofi are currently conducting clinical trials in the United States of a vaccine containing viral protein Lyke and her colleagues. Design their study so they can add more such vaccines later.

“Behind the scenes, we are working on other contracts. So we can move more boosters into trials,” she said. Those additional boosters could include boosters customized for variables, such as boosters developed by Pfizer-BioNTech

Other mixed booster trials in progress in the UK Scientists are vaccinating volunteers from AstraZeneca, CureVac, Johnson & Johnson, Moderna, Novavax, Pfizer-BioNTech and Valneva as boosters. ImmunityBio is testing the vaccine in South Africa as a booster for Johnson & Johnson’s vaccine, while Sanofi is preparing. Test the vaccine as a booster for vaccines from several other companies.

The NIH trial may begin to take effect immediately in the coming weeks. If fading vaccines and rising variants lead to new infections this winter, Lyke wants to have information she can share with policymakers.

“For us, getting answers as quickly as possible is extremely important,” she said. “We don’t have that kind of luxury.”

How about everyone who hasn’t received their first dose yet?

Hensley said it’s good to be prepared for the possibility of a booster. But he hopes they won’t become a distraction from the urgent need to provide the first drug to billions of people around the world.

“If more and more people are immediately protected Viruses have fewer hosts to infect. and less likely to evolve into new species,” he said.

“I want to see these vaccines spread all over the world. Because I want to protect people around the world,” Hensley added. “But even if you only care about yourself You should try to stay behind too. Because that is the only way for you to end the epidemic and limit the capacity of the variables that will arise.”

This article originally appeared in The New York Times.

© 2021 The New York Times Company


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