The drugmaker Moderna asked the Food and Drug Administration on Wednesday to expand emergency use authorization of its Covid-19 vaccine booster to all people ages 18 and older.
Moderna's booster shot is authorized for people 65 and older, those living in long-term care facilities and adults with underlying medical conditions or who are at high risk of exposure to the coronavirus because of their jobs. It's given six months after the second dose of the primary vaccination series.
The FDA is expected to soon authorize Pfizer's booster shot for all adults. If the Moderna booster is also authorized, booster shots would be available to all adults in the U.S.
But would all adults need booster shots? That remains unclear, said Dr. Jesse Goodman, a professor of medicine and infectious diseases at Georgetown University Medical Center.
"By and large, healthy, younger people who have been vaccinated are handling breakthrough infections well," said Goodman, a former chief scientist with the FDA.
"People have to realize giving a third dose of vaccine to healthy young people is not going to affect the pandemic," he said. "The way we're going to do that is by getting unvaccinated people immunized."
While the Moderna vaccine has been shown to be safe overall, it does have a small but elevated risk for myocarditis, a type of heart inflammation, particularly in young men.
“These cases are typically mild,” Moderna’s chief medical officer, Dr. Paul Burton, said at a news briefing this month. “While we don’t fully understand the reasons and the etiology behind this, we think that it may be driven by testosterone.”
There have been concerns that a third dose could possibly raise risk further, but Burton said no cases of myocarditis have been reported in clinical trials of booster doses in this age group, adding that the benefits of vaccination far outweigh any risks.
A Centers for Disease Control and Prevention advisory group is scheduled to meet Friday to discuss Pfizer’s booster shot for people ages 18 and older.
Moderna's booster is given at a half-dose of the primary vaccination series: 50 micrograms, compared to 100 micrograms.
Some states, as well as New York City, have already opted to make Moderna boosters available to all adults, bypassing official action from the FDA and the CDC.