On Wednesday night, the U.S. Food and Drug Administration officially authorised the use of boosters for eligible people vaccinated against covid-19 with either the Moderna and Johnson & Johnson vaccine. They’ve also given their blessing for people to mix and match different types of vaccines for their booster — a likely welcome decision for the millions of Americans who received only the single-shot and less effective J&J vaccine.
The announcement comes less than a week after the FDA’s advisory committee discussed the data supporting the use of these boosters as well as mixing and matching them. The outside experts recommended both boosters, though no official stance was taken on whether people should be allowed to mix-and-match. A month earlier, the FDA and CDC authorised the use of a Pfizer booster for eligible Americans, though only for those who had originally taken the Pfizer shot.
“Today’s actions demonstrate our commitment to public health in proactively fighting against the covid-19 pandemic,” said Acting FDA Commissioner Janet Woodcock in the agency’s announcement. “As the pandemic continues to impact the country, science has shown that vaccination continues to be the safest and most effective way to prevent covid-19, including the most serious consequences of the disease, such as hospitalisation and death.”
Like the Pfizer booster, the Moderna booster will be recommended for all Americans over the age of 65, as well as Americans over 18 who are either at high risk of severe covid-19 due to their pre-existing health issues or who are at high risk of frequent exposure to the virus, particularly health care workers. Both mRNA shots are recommended to be taken six months after the second shot, though Moderna’s booster dose will be at half-strength to the original (Moderna’s doses were already larger than Pfizer’s). The J&J booster will be recommended for everyone who took the original single shot. It should be taken as soon as possible, two months or later after the first dose. Regardless of the original vaccine taken, the FDA has also sanctioned the use of a different vaccine as a booster, a move meant to accelerate the rollout of these shots.
Some experts have been sceptical about the benefits of boosting the general population. But several lines of evidence have shown that older individuals are more likely to experience waning immunity and that boosters can at least temporarily restore the vaccine’s effectiveness against infection and illness in these groups. Just today, results released from a randomised clinical trial by Pfizer/BioNTech found that the vaccine’s effectiveness against the coronavirus was around 95% following a booster dose compared to fully vaccinated people who received a placebo shot instead. The median age of participants was 53, though some were as young as 16, and the trial occurred during a time when the Delta variant had become widespread.
Some data has also pointed to the improved effectiveness in immunity in those who use a mix-and-match approach with different types of vaccines, such as the mRNA vaccines by Moderna and Pfizer and the adenovirus-based vaccines from J&J and AstraZeneca. But the FDA notes that it will continue to monitor the real-world evidence on booster doses as well as mix-and-match shots. And it remains possible that more Americans will be advised to get a booster vaccine eventually.
“We will work to accrue additional data as quickly as possible to further assess the benefits and risks of the use of booster doses in additional populations and plan to update the healthcare community and public with our determination in the coming weeks,” Peter Marks, director of the FDA’s Centre for Biologics Evaluation and Research, said in the announcement.
The FDA is responsible for authorizing or approving new drugs or vaccines. But the CDC also has to officially recommend which populations should receive these shots before they would be widely available. Later today, an advisory committee assembled by the CDC will meet to discuss these latest developments concerning the Moderna/J&J booster doses as well as mixing and matching vaccines, and a final decision by the CDC may come before the weekend.