There hasn’t been enough research on how much protection a fourth dose can provide, medical professionals told CNBC.
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Countries have begun providing a fourth dose of the Covid-19 vaccine to vulnerable groups, but medical professionals are hesitant about whether it will benefit the wider population.
So far, the US Food and Drug Administration has allowed the fourth injection only for those 50 and older, as well as those who are immunocompromised. The US Centers for Disease Control and Prevention was skeptical about the need for a fourth dose for healthy adults in the absence of a clearer public health strategy.
These decisions came as a study from Israel found that although a fourth dose of the Pfizer-BioNTech vaccine provides protection against serious illness for at least six weeks after the injection, it provides only short-term protection against infection, which fades after Only four weeks. .
There is no “good guide” yet
The medical consensus so far is that not enough research has been done on how much protection a fourth dose can provide.
WHO chief Somya Swaminathan said the WHO had not made a formal recommendation for a fourth dose, and “there is no good evidence at the moment” that it would be beneficial.
“What we know from immunology is that if you give another booster, you’ll see a temporary increase in neutralizing antibodies,” Swaminathan told CNBC in an interview. “But what we’ve also seen is that these neutralizing antibodies will disappear very quickly.”
“This happened after the third dose. It happened again after the fourth dose,” she added.
Paul Goepfert, a professor of medicine at the University of Alabama, shared this view, saying that “the fourth dose doesn’t do much…I’m not sure we need to go out and just jump up and down screaming that everyone needs to get away.”
Because the study from Israel shows that a fourth dose can provide protection against serious disease, countries such as Israel, Denmark and Singapore have provided a second booster dose to high-risk groups.
“Rather than saying that protection is diminished, I would say that this booster effect is stronger soon after the vaccine is given, but it remains protective overall,” Ashley Saint said. John, associate professor of medicine at Duke-NUS College of Medicine.
“Importantly, there has been no decline in protection from severe disease, which is the most important impact of vaccination we aim to achieve,” she added.
Annual booster shots?
Questions are raised about the need for more booster shots because the emergence of more variants of Covid may require more targeted vaccines.
Anthony Fauci, the White House’s chief medical advisor, told NBC News in January that people may need to get booster injections every year or two.
However, universal vaccine approaches may not continue to work.
It is possible that high-risk groups – such as the elderly – may need an annual vaccination, Swaminathan said. But “it is not clear whether a healthy adult would need a regular annual dose.”
It is also important to note that current vaccines being administered may not work for future variants of Covid-19, she said.
Swaminathan added that if the virus changes so much that you need to change the formulation of your vaccine, you will not need another injection. “The challenge with changing the vaccine formula is that you’re always playing catch-up.”
Only time will tell how long a population should take a booster dose, but a safer approach would be ‘planning a booster dose each year, possibly combining it with the flu vaccine,’ said Goepfert.
On Tuesday, the World Health Organization announced that new weekly deaths due to Covid had fallen to the lowest level since March 2020.
But the most contagious variant of omicron BA.2 remains the dominant strain in the United States, making up 68.1% of all cases in the country during the week ending April 23, according to data from the CDC.
Although experts speculate that the BA.2 variant is unlikely to be more severe than the original omicron strain, it should remain a concern.
“I think infections are going to continue … it’s been captured in most parts of the country. But in terms of severe infections, I think that’s going to continue to decrease,” Goepfert said.
Patients from locations with adequate vaccination coverage may only suffer from “mild or manageable illness” and this would reduce “the burden on the health care system compared to waves of pre-vaccination for Covid,” St. John said.
“Just like studying for an exam, a booster vaccine can stimulate memories of the immune system and increase performance during the real exam,” she added.