On Thursday evening, the Food and Drug Administration (FDA) authorized third doses of both Pfizer and Moderna vaccines in the U.S. in an effort to mitigate the extremely viral Delta variant. But according to the amended emergency authorization, only a few groups of people will be eligible for third shots — or booster shots — in the U.S.
The FDA's announcement comes shortly after the World Health Organization implored wealthy countries to avoid giving out third doses until countries with fewer vaccines can catch up. On August 4, WHO Director-General Tedros Adhanom Ghebreyesus, PhD, asked for a moratorium on booster shots until at least the end of September, stating that hundreds of millions of people around the world still don't have access to first doses.
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"So far more than 4 billion vaccine doses have been administered globally. More than 80% have gone to high- and upper-middle-income countries, even though they account for less than half of the world's population," Dr. Ghebreyesus said. "We cannot and we should not accept countries that have already used most of the global supply of vaccines using even more of it while the world's most vulnerable people remain unprotected."
The FDA, however, has made it clear that these boosters will only be available to about 3% of U.S. adults, accounting only for people who suffer from immunodeficiencies. “Today’s action allows doctors to boost immunity in certain immunocompromised individuals who need extra protection from COVID-19,” Janet Woodcock, MD, the FDA's acting commissioner, said in a statement.
So, who exactly is eligible for a third dose? Per the FDA, this amendment only includes "solid organ transplant recipients or those who are diagnosed with conditions that are considered to have an equivalent level of immunocompromise." (Transplant recipients are often put on immunosuppressive medications, making them at a much higher risk of contracting severe cases of COVID-19.)
Earlier on Thursday, Anthony Fauci, MD, the chief medical adviser to President Biden, also suggested that severely immunocompromised adults would benefit greatly from a third shot. According to Dr. Fauci and the FDA, those with immunocompromised systems have shown a "weak response" to two doses of the vaccine, often caused by existing conditions of conflicting medical treatments.
However, both Dr. Fauci and the FDA have insisted that boosters are not yet needed for anyone outside of this 3% group. Although a (not-yet peer reviewed) Pfizer study shows that efficacy of their vaccine may drop over time — four months after the second dose, efficacy may be around 84%, compared to a 96% efficacy up to two months post-jab — experts remain divided about the necessity of a third shot altogether. In this latest announcement, Dr. Woodcock also explicitly stated that "others who are fully vaccinated are adequately protected & do not need an additional dose of COVID-19 vaccine at this time." Data from the CDC has indicated that over 1 million people may have gotten unauthorized third shots.
When asked about WHO's concerns over access to vaccines around the world, Dr. Fauci told NPR that he feels "very strongly" about the U.S.'s position in helping to distribute vaccines. "I've been very vocal about that, that we have a responsibility as a rich nation — and other rich nations — to make sure that there's equity in the ability to distribute and the accessibility of vaccines," he said. "However, the United States is really doing both. If you look at what we are doing, we are essentially doing more than the rest of the world combined."