Health professionals are skeptical of a fourth dose of Covid vaccine

There hasn’t been enough research on the protection a fourth dose can offer, medical professionals told CNBC.

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Countries are beginning to offer a fourth dose of the Covid-19 vaccine to vulnerable groups, but medical professionals are unsure whether this would benefit the general population.

The U.S. Food and Drug Administration has so far authorized a fourth vaccine only for people age 50 and older, as well as immunocompromised people. And the US Centers for Disease Control and Prevention was skeptical of the need for a fourth dose for healthy adults in the absence of a clearer public health strategy.

The decisions came as an Israeli study found that although a fourth dose of the Pfizer-BioNTech vaccine provides protection against serious illnesses for at least six weeks after the vaccine, it only provides short-term protection. against infection, which subsides after just four weeks. .

No “good evidence” yet

So far, the medical consensus is that there hasn’t been enough research on how much protection a fourth dose can provide.

The World Health Organization has not given an official recommendation on a fourth dose, and “there is no strong evidence at this stage” that it will be beneficial, the WHO’s chief scientist said, Soumya Swaminathan.

“What we know from immunology is that if you give another booster, you’ll see a temporary increase in neutralizing antibodies. But what we’ve also seen is that those neutralizing antibodies will decline quite rapidly,” Swaminathan told CNBC in an interview.

A fourth dose doesn’t really do much…I’m not sure we need to go out and jump up and down yelling that everyone needs to get on board.

Paul Goepfert

professor at the University of Alabama

“It happened after the third dose. And it happened again after the fourth dose,” she added.

Paul Goepfert, professor of medicine at the University of Alabama, shared this view, saying that “a fourth dose doesn’t really do much … I’m not sure we need to get out and jumping up and down yelling that everyone has to get on board.”

Because the study in Israel shows that the fourth dose can provide protection against severe disease, countries such as Israel, Denmark and Singapore have made a second booster shot available to high-risk groups.

“Rather than say that protection wanes, I would say that this boost effect is strongest soon after the vaccine is given, but remains protective overall,” said Ashley St. John, associate professor at the Duke-NUS Medical School.

“Importantly, there was no decrease in protection against severe disease, which is the most important effect of vaccination that we aim to achieve,” she added.

Annual reminders?

Questions are being raised about the need for more boosters as the emergence of more Covid variants may require more targeted vaccines.

Anthony Fauci, the White House’s chief medical adviser, told NBC News in January that people might need booster shots every year or two.

However, general vaccine approaches may not continue to work.

It’s possible that high-risk groups — like the elderly — will need an annual vaccine, Swaminathan said. But “it is not clear whether a healthy adult will need a regular annual injection.”

It’s also important to note that currently administered vaccines may not work for future variants of Covid-19, she said.

If the virus “changes so much that you have to change the composition of your vaccine, you won’t need another vaccine,” Swaminathan added. “The challenge of changing the makeup of the vaccine is that you’re always catching up.”

Goepfert said “only time will tell” how much longer people need to take boosters, but the safest approach would be to “plan a booster every year, and maybe combine it with the vaccine against flu”.

Sub-variant of Omicron

The WHO announced on Tuesday that new weekly Covid deaths had fallen to the lowest level since March 2020.

But the more contagious omicron BA.2 subvariant remains the dominant strain in the United States, accounting for 68.1% of all cases in the country in the week ending April 23, according to the CDC data.

Although experts predict that the BA.2 subvariant is unlikely to be more severe than the original omicron strain, it should remain of concern.

“I think the infections are going to continue… they’ve taken over most parts of the country, Goepfert said. “But in terms of serious infections, I think it’s going to continue to be less and less.”

Patients from places with adequate vaccine coverage would only experience “mild or manageable illness” and that would reduce “the burden on the healthcare system from waves of pre-Covid vaccines,” St. John said.

“Like studying for an exam, a vaccine booster can trigger immune system memories and boost performance in the actual test,” she added.

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