Do I need a 4th COVID vaccine? Experts explain how to decide

  • Pfizer and Moderna have asked the FDA to allow adults in the United States to receive 4th dose boosters.
  • Experts say boosting again with the same injections may not be the best strategy for this virus.
  • Fourth injections may be prudent for certain risk groups.

Pfizer and Moderna are both asking the US government to greenlight fourth doses of their COVID-19 vaccines.

Last Tuesday, Pfizer announced that it had submitted an application to the US Food and Drug Administration “for an emergency use authorization (EUA) of a supplemental booster dose for adults 65 years of age and older.”

This was after Pfizer CEO Albert Bourla told CBS over the weekend that Americans should prepare for COVID-19 reminders every year, like what happens when people line up to get their flu shots every fall.

“Right now the protection we’re getting from a third party is pretty good, actually pretty good for hospitalizations and deaths,” Bourla said, while noting his concern that “the length of protection doesn’t last very long.” long time”.

On Thursday night, Moderna also said it submitted an EUA to the FDA for the fourth doses of its COVID-19 vaccine. Moderna’s demand is broader than Pfizer’s. According to the company, EUA would allow a fourth dose to be administered to all adults, letting healthcare providers “determine the appropriate use” of boosts in their patients, weighing factors such as age and a person’s comorbidities.

However, independent infectious disease experts, some of whom advise the FDA on vaccines, told Insider that the decision to give people in the United States a fourth vaccine might not be the most prudent idea, for at least. three main reasons.

Here is a brief overview of the latest research and independent expert opinions on whether fourth doses are right for you.

1: The virus has changed. Vaccines haven’t been.

The MTA poster says

A COVID-19 vaccine reminder ad in the New York City subway on January 9, 2022.

Michael Nagle/Xinhua via Getty Images


The vaccines currently offered by Moderna and Pfizer are still the original formulations, which means they are not suitable for circulating COVID-19 variants, such as Omicron, and the rapidly spreading Omicron subvariant, BA.2.

All of the vaccines we have now were developed based on a virus that was sequenced in Wuhan in January 2020. In the two-plus years since then, the virus has evolved, but the vaccines have not.

“I personally don’t think pharmaceutical companies should be talking about boosting with the same vaccines we are,” Dr. James Hildreth, an infectious disease expert who advises the FDA on vaccines, told Insider. “I would much rather see the focus on looking at the sequences from the variants that we have dealt with and trying to create a vaccine that would offer protection against them, rather than just giving people a fourth injection.

Hildreth fears that by continuing to use vaccines suitable for a 2-year-old virus, we are creating new problems. Boosting with an expired injection could produce antibodies that are of little value against circulating virus strains. Or, as the virus evolves, it’s also possible that it could learn to develop better resistance to vaccines. More frequent boosts tailored to an older version of the virus could speed up this process.

“I hate to even talk about it, but there is evidence from mouse studies that repeated immunizations, with intervals that are too short, can actually start to induce tolerance,” Hildreth said. “And that’s the last thing you want.”

A big problem with modifying existing vaccines, however, is that it’s still unclear what kind of FDA review a variant-matched mRNA vaccine would require before it could be distributed. In addition to variant-specific stimulants, several independent research groups and pharmaceutical companies are also working on pan-coronavirus vaccines that would target different strains of coronaviruses at once, hoping to achieve broad immune protection against future coronaviruses that will are not even in circulation yet, in addition to those that are spreading now. These pan-coronavirus vaccines are still at least a few years away, at best.

2: We haven’t seen good data that the 4th dose is needed, or anything helpful, for most people

The data we have on boosters so far only suggests that the elderly, as well as those with underlying medical conditions, will derive good benefit from the fourth dose. There’s no excellent data showing the benefit of additional booster shots younger and intact immune systems, when it comes to preventing serious illness.

A recent CDC study suggested that vaccine efficacy against severe consequences, including mechanical ventilation and death during the peak of the Omicron wave in early January, was 88% with two injections and 94% with three injections. , suggesting that a booster injection provides only a marginal improvement in vaccine efficacy. , for most people. Another CDC study showed that more than 96% of fully vaccinated people who were hospitalized with COVID while on Omicron had preconditions, and the same was true for 9 out of 10 boosted adults hospitalized with Omicron.

Even Moderna executives agree that additional booster programs, at this point, should be largely focused on the most vulnerable patients.

Moderna President Stephen Hoge told Insider last week that “for those who have cancer, COVID can actually be a life-threatening disease, even after vaccination,” but he said further increases will not happen. are not necessarily necessary for members of the general public under the age of 65. , without preconditions.

3: Fourth doses provide only marginal benefits so far

Israel has already tried fourth doses of Pfizer and Moderna vaccines on young, healthy populations, with only mediocre results. A study of more than 1,000 Israeli healthcare workers who received a fourth injection four months after their initial booster, suggested there was no additional boost to the immune system with a fourth dose, beyond of the protection obtained with three doses. While a fourth dose temporarily boosted antibody levels to where they were after a third vaccine, there was only a “marginal” temporary benefit to giving young, healthy populations another shot.

“We currently have vaccines that offer protection against serious diseases,” Dr. Barney Graham, one of the co-inventors of Moderna’s COVID-19 vaccine at the National Institutes of Health, told Insider, saying that the vaccines ” work more as we expected” at this point, and that mild COVID-19 infections in healthy young people who have been vaccinated are not necessarily a major cause for concern in the future.

“That’s actually part of how vaccines work – you protect the lower respiratory tract, and upper respiratory tract exposures that cause very mild or no disease will stimulate responses and keep you immune,” he said.

A recent study of more than 422,000 people across the United States who took Johnson and Johnson’s much-maligned single-shot vaccine also suggested it worked well enough to prevent hospitalizations and deaths, although this discovery is slightly less true among the most vulnerable. patients and in the elderly.

“Let’s identify those who are most vulnerable and most susceptible to serious illness, hospitalization and possibly death, and make sure we do everything we can to protect them,” Hildreth said.

Boosting the US while ignoring where new variants might emerge is not a strategy backed by experts

Rather than considering a fourth dose for large swaths of those already vaccinated in the United States this summer, Graham says more vaccines should be sent to the lower half of the globe. He fears that COVID-19 will spread rapidly there as temperatures drop, and that it could give rise to a worrying new variant that could “more completely elude all of our current vaccines and monoclonal antibodies.”

“Can we please just get the southern hemisphere vaccinated before June?” he said. “We have things that work, at least to protect us against serious illnesses, and the question is: are we going to deploy them where it could help the most?”

“Generally the reason we’ve had to deal with variants is that we didn’t immunize the world fast enough,” Graham added.

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