What you need to know about a fourth COVID-19 vaccine dose

Most people 12 years and older are considered “up-to-date” with their COVID-19 vaccines if they have received either three doses of the mRNA injections from Pfizer-BioNTech or Moderna, or two doses of the Janssen Johnson & Johnson vaccine. But some public health experts say another dose may be needed in the coming months.

On March 15, Pfizer and BioNTech applied to the US Food and Drug Administration (FDA) for approval for a fourth dose of their vaccine in people age 65 and older. In recent days, Albert Bourla, CEO of Pfizer, has said he believes that one day everyone will need a fourth dose to help prevent infections (a move that would have clear business benefits).
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To approve a fourth injection, the FDA will consider alarming signs that immunity from the vaccines is beginning to wane, which could leave people more vulnerable to the more serious effects of COVID-19. Recent data published by the US Centers for Disease Control and Prevention (CDC) shows that protection from hospitalization for COVID-19 declined, even after a booster dose of either the Pfizer-BioNTech or Moderna vaccines. From August 2021 to January 2022 — a time span that includes waves of both Delta and Omicron variants — the booster was 91% effective in protecting against hospitalization in the first two months after people received it, but dropped to 78% four months ago. then the shot. Vaccine efficacy against emergency room visits and emergency care for COVID-19 symptoms followed a similar decline, from 87% up to two months after the booster to 66% four to five months after the booster.

“We don’t know when you come six months, seven months, or eight months after the third dose, whether that 78% will drop to 60%, 50%, or 40%,” says Dr. Anthony Fauci, the White House chief medical adviser on COVID-19 and director of the National Institute of Allergy and Infectious Diseases. “That’s why you’re going to hear serious consideration about giving a fourth boost to the elderly and those with certain underlying health conditions. What we might see in the reasonable future is individuals, based purely on age and perhaps some underlying health conditions that have yet to be identified, would get an immediate boost.”

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The CDC is already recommending a fourth mRNA vaccine dose for people with weakened immune systems, including transplant patients and those undergoing chemotherapy for cancer, and other countries have similar guidelines. Israeli health officials have gone one step further; on Jan. 22, as cases and hospitalizations crept up, the country approved a fourth dose of the Pfizer-BioNTech mRNA vaccine for health professionals and people over 60 years of age. The decision was based on early data from Israel’s Ministry of Health and researchers from several Israeli universities that showed that of nearly one million vaccinated people over the age of 60, a fourth dose of the vaccine offered up to twice the protection against infection, and up to three times more. the protection against serious illness, compared with those who received three doses.

There is also mounting evidence that all forms of vaccine-induced protection continue to decline. Scientists have long known that the antibodies people make immediately after vaccination have relatively short lives, but the vaccine prompts the body to also produce other immune defenses, including T cells, which are generally more durable. But even those responses begin to subside after several months, says Dr. Otto Yang, a professor of medicine, infectious diseases, microbiology, immunology and molecular genetics at the University of California, Los Angeles. That means existing vaccine regimens may need to be supplemented with another booster dose to keep both antibody and T cell counts high enough to protect people from serious illness, he says.

But whether everyone needs an extra vaccine dose, and whether or not we can anticipate getting one every year or every few years, depends on what we want the vaccines to achieve. The vaccines are not designed to prevent people from becoming infected with the virus, but to prevent them from becoming extremely ill with COVID-19 and to avoid requiring hospitalization and intensive care. Remembering that goal, says Dr. Paul Offit, director of the Vaccine Education Center and professor of pediatrics at Children’s Hospital in Philadelphia, is helpful when considering whether a fourth dose is necessary for most people.

“We were hung up on the word ‘breakthrough’ when describing mild illness,” he says, referring to the term for any infection that occurs in vaccinated and boosted people (most of which were mild or even asymptomatic). “But that’s a win — it meant the vaccine worked for you and protected you from a serious illness. We’ve developed a zero-tolerance strategy that we need to overcome: the idea that it’s not okay to have a mild illness after you have been vaccinated.”

If the goal of a COVID-19 vaccine is to protect people from serious illness, Offit says there’s still not enough data to support the need for a booster for most healthy adults. “I think we have to accept the idea that this is a three-dose vaccine in some groups and a two-dose vaccine in others,” Offit says.

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Offit, who serves on the FDA’s Vaccine Advisory Committee of Independent Experts that reviews data and makes recommendations to the FDA on whether or not a vaccine is safe and effective, says it’s trying to protect the world’s population from mild disease. with continued booster dose it’s not a realistic or practical public health goal. The question becomes a tradeoff between any marginal benefit in protecting against mild disease and potential side effects, including the risk of inflammation of heart tissue for the mRNA vaccines. “Everything has a cost, including incentives,” he says. “If it doesn’t benefit you in protecting you against serious diseases, then you have to consider the side effects.”

Fauci says health officials will closely monitor the number of hospital admissions among vaccinated and fortified people in the coming weeks and months; if it creeps up, it would be a sign of a worrying decline in protection, even against serious illness, which could warrant another booster dose. “We don’t know right now if we’ll need it, but as long as this virus is around I wouldn’t be surprised if we need another shot than we’ve had,” he says.

He and others also don’t expect to continue boosting as new variants emerge. Until now, that strategy stemmed from the urgent need to tackle the virus in as many people as possible as quickly as possible. But it’s not a sustainable or practical long-term game plan. “We’ve chased our tails with every variant, and we’ll be left behind forever” [the virus]said Dr. Kirsten Lyke, a professor of medicine at the University of Maryland who led studies on mixing and matching different types of COVID-19 vaccines.

But now that much of the US population has some degree of immunity through infection, vaccination, or both, the National Institutes of Health are launching new studies looking for a more targeted approach to potential booster shots. Instead of reacting to new variants as they emerge and hoping that existing vaccines will continue to protect against serious disease, scientists there are mapping SARS-CoV-2 mutations and trying to design vaccines against broad sets of changes that ideally would number of different but related strains that the virus may generate in the future. The study will involve up to 1,500 people at 25 locations. “By mid-summer, we want to have all the data together so we can make a more scientific assessment of whether additional boosters will work, whether we’ll need them, and which ones we might need to use,” Lyke says.

Whether a fourth dose will be recommended for most Americans likely depends on future hospitalizations among vaccinated and boosted people; if they continue to increase, that may prompt health officials to consider recommending another booster dose. In the meantime, Fauci says scientists at the National Institute of Allergy and Infectious Diseases Vaccine Research Center are investigating whether that extra dose should come from the same vaccine people received, or if that extra dose should be combined with a new vaccine that targets on a specific variant, such as Omicron. So far, the original booster produces similar immune responses to those generated by variant-specific boosters in non-human primates. “Given that we have declining immunity, we may need a regular boost at intervals that have yet to be determined,” Fauci says.

This post What you need to know about a fourth COVID-19 vaccine dose

was original published at “https://time.com/6157560/fourth-covid-19-vaccine-dose/”