Washington: The US Food and Drug Administration (FDA) has given authorization for the emergency use of third dose of both Moderna and Pfizer vaccines against COVID-19 for immunocompromised people.
Importantly, the FDA's decision only applies to this high-risk group, estimated to be no more than 3% of US adults. It's not an opening for booster doses for the general population.
"The country has entered yet another wave of the COVID-19 pandemic, and the FDA is especially cognizant that immunocompromised people are particularly at risk. After a thorough review of the available data, the FDA determined that this small, vulnerable group may benefit from a third dose of the Pfizer-BioNTech or Moderna Vaccines," acting FDA Commissioner Janet Woodcock said on late Thursday, as quoted by the body's statement.
"Today's action allows doctors to boost immunity in certain immunocompromised individuals who need extra protection from COVID-19. As we've previously stated, other individuals who are fully vaccinated are adequately protected and do not need an additional dose of COVID-19 vaccine at this time," Woodcock added.
It's harder for vaccines to rev up an immune system suppressed by certain medications or diseases, so those patients don't always get the same protection as otherwise healthy people - and small studies suggest for at least some, an extra dose may be the solution.
Instead, health authorities consider the extra dose part of the initial COVID-19 vaccine prescription for the immune-compromised. Separately, US health officials are continuing to closely monitor if and when average people's immunity wanes enough to require boosters for everyone - but for now, the vaccines continue to offer robust protection for the general population.
The Centers for Disease Control and Prevention is expected to formally recommend the extra shots for certain immune-compromised groups after a meeting on Friday of its outside advisers.
Transplant recipients and others with suppressed immune systems know they're at more risk than the average American and some have been seeking out extra doses on their own, even if it means lying about their vaccination status. The change means now the high-risk groups can more easily get another shot - but experts caution it's not yet clear exactly who should.
Dr Dorry Segev, a transplant surgeon at Johns Hopkins University who is running a major National Institutes of Health study of extra shots for organ recipients said that for some people, a third dose "increases their immune response. Yet for some people it does not seem to. "We don't quite know who's who yet."
One recent study of more than 650 transplant recipients found just over half harbored virus-fighting antibodies after two doses of the Pfizer or Moderna vaccines - although generally less than in otherwise healthy vaccinated people.
Another study of people with rheumatoid arthritis and similar autoimmune diseases found only those who use particular medications have very poor vaccine responses.
There's little data on how well a third dose works, and if it causes any safety problems such as an increased risk of organ rejection.
