Medical professionals are skeptical on a fourth Covid vaccine dose

There hasn’t been enough research on how much 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 undecided on whether it would benefit the wider population.

The U.S. Food and Drug Administration has so far authorized a fourth shot only for those aged 50 and above, as well as those who are immunocompromised. And the U.S. 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.

Those decisions came as a study from Israel found that although a fourth dose of the Pfizer-BioNTech vaccine offers protection against serious illness for at least six weeks after the shot, it provides only short-lived protection against infection, which wanes after just four weeks.

No ‘good evidence’ yet

Annual booster shots?

Questions are being raised over the need for more booster shots as the emergence of more Covid variants may require more targeted vaccines.

Anthony Fauci, White House chief medical advisor, told NBC News in January that people may need to get booster shots every year or two.

However, blanket vaccine approaches may not continue to work.

It is possible that high-risk groups — such as the elderly — may need an annual vaccine, said Swaminathan. But “it’s not clear whether a healthy adult is going to need a regular annual shot.”

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

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

Goepfert said “only time will tell” how long more the population has to take booster shots, but the safest approach would be to “plan on a booster every year, and maybe combine it with the flu vaccine.”

Omicron subvariant

The WHO announced on Tuesday that weekly new 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, making up 68.1% of all cases in the country during the week that ended on April 23, according to data from the CDC.

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

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

Patients from locations with adequate vaccination coverage would experience only “mild or manageable disease” and this would reduce “burden on the healthcare system compared to waves of Covid pre-vaccines,” St. John said.

“Just like studying for an exam, a vaccine booster can trigger immune system memories and increase performance during the real test,” she added.