Health experts told CNBC there’s still not enough research on how protective a fourth dose might be.
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Countries are starting to provide a fourth dose of the Covid-19 vaccine to vulnerable groups, but health experts have yet to decide whether it will benefit populations. .
US Food and Drug Administration to date Only the fourth shot is allowed for people 50 years of age and older, as well as those who are immunocompromised. And the US Centers for Disease Control and Prevention has skepticism about the need for a fourth dose in healthy adults in the absence of a clearer public health strategy.
Those decisions come as one learn from Israel found that although the fourth dose of the Pfizer-BioNTech vaccine provided protection from serious illness for at least six weeks after injection, it provided only short-term protection against infection, which goes away after just four weeks.
The medical consensus to date is that there hasn’t been enough research into how protective a fourth dose might be.
The World Health Organization has not made an official recommendation for a fourth dose and “there is not any solid evidence at this time” that it would be beneficial, said WHO chief scientist Soumya Swaminathan. .
“What we know from immunology is that if you give another booster shot, you’ll see a temporary increase in neutralizing antibodies,” Swaminathan told CNBC in an interview.
“This 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, shares that view, saying that “the fourth dose really doesn’t do much… I’m not sure we need to get out and just jump up and down and screaming. that people need to get on board.”
Because research from Israel shows that a fourth dose can protect against critical illness, countries such as Israel, Denmark and Singapore have made a second booster shot for high-risk groups.
Ashley St. John, an associate professor at Duke-NUS School of Medicine, said: “Rather than saying that the protection wears off, I would say that this enhanced effect is strongest soon after the vaccine is administered, but it still has an overall protective effect,” Ashley St. John, an associate professor at Duke-NUS Medical School, said.
“It’s important that there’s no decline in protection against severe illness, which is the main effect of vaccination that we want to achieve,” she added.
Questions are being raised about the need for booster shots as the emergence of more Covid variants may require more targeted vaccines.
Anthony Fauci, chief medical adviser to the White House, told NBC News in January that people may need booster shots every year or two.
However, covered vaccination methods may not continue to work.
It is possible that high-risk groups – such as the elderly – may need annual vaccinations, Mr. Swaminathan said. But “it is not clear whether a healthy adult needs to be vaccinated every year.”
It should also be noted that current vaccines in use may not work against future variants of Covid-19, she said.
If the virus “changes so much that you need to change the composition of the vaccine, then you won’t need another shot,” Swaminathan added. “The challenge of changing vaccine composition is that you’re always playing catch-up.”
“Only time will tell,” says Goepfert, “how often” the population needs a booster shot, but the safest approach is “to schedule a booster every year and possibly combine it with the flu vaccine.” .”
WHO announced every Tuesday that The number of new Covid deaths has fallen to the lowest level since March 2020.
However, the more contagious omicron differential strain BA.2 remains the dominant virus strain in the United States, accounting for 68.1% of all infections in the country for the week ending April 23, according to data data from the CDC.
Although experts predict that the BA.2 subvariable is not likely to be more severe than the original omicron strain, it should still be a concern.
“I think the infection is going to continue … it’s invaded most parts of the country,” Goepfert said.
Patients coming from sites with full vaccination coverage will experience only “mild or manageable illness” and this will reduce the “burden on the health care system compared with vaccination rounds”. before of Covid”, St. John said.
She added: “Just like studying for an exam, booster vaccines can trigger the immune system’s memories and boost performance during a reality check.