US Food and Drug Administration has recently approved booster doses for the Moderna and Johnson & Johnson COVID-19 vaccines. The agency has also allowed mix-and-match boosters — eligible people who are already fully vaccinated can get a booster dose of any of the three vaccines, regardless of which they started with.
FDA cleared third Moderna shots for vulnerable groups, including people 65 years of age and older, those who are at high risk of severe disease, and people at high risk of exposure to COVID-19 at work.
The booster for the Moderna vaccine, though, will be a half-dose. Both vaccines are mRNA vaccines that contain tiny snippets of the coronavirus genetic material. But the Moderna vaccine has a larger dose: it’s 100 micrograms, compared with the 30 micrograms in the Pfizer / BioNTech shot. The company says a third, 50 microgram half-dose of the Moderna vaccine could have fewer side effects while still giving strong protection.
The FDA is opening up second, booster doses of the Johnson & Johnson vaccine to everyone who got that shot. Boosters for the Johnson & Johnson vaccine can start two months after the first dose, unlike the six-month wait for the Pfizer / BioNTech and Moderna boosters.
The Johnson & Johnson shot was originally authorized as a one-shot vaccine, which experts hoped would make it logistically easier to deliver to low-resource areas and to give to people who may not want to come back for a second shot. Still, only around 15 million people in the United States have been immunized with this vaccine.
Johnson & Johnson says that a second booster dose bumps the vaccine’s efficacy against symptomatic cases of COVID-19 to 94 percent, in line with the initial clinical trial results for the gene-based shots.
The FDA cleared the additional shot even though the agency was critical of the quality of data provided by Johnson & Johnson in its initial evaluation of the need for a booster. The agency said that the test used to check antibody levels in people who got a second dose wasn’t sensitive enough.
In a statement, FDA’s Center for Biologics Evaluation and Research director, Peter Marks said: “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.”
