The FDA will decide whether to authorize the boosters based off the advisory panel's recommendations.
FDA advisers unanimously approved the Moderna half-dose booster for seniors and other at-risk groups, clearing the way for full FDA approval later this month.
The Vaccines and Related Biological Products Advisory Committee, in a nonbinding vote, advised that the booster shot be administered after a period of six months following the second dose for adults 65 years of age and older and for others who are immunocompromised.
Based off the advisory panel's recommendations, the FDA will then decide whether to authorize the boosters.
The Centers for Disease Control and Prevention then have the final say, which likely will occur during the third week in October.
The panel also discussed when boosters should be recommended to all adults over 18, saying that it currently is too soon to consider that issue.
The third shot of the Pfizer vaccine was already approved recently for older adults, individuals who are at risk because of medical conditions, and people who work or live in high-risk settings in which they may be easily exposed to the COVID-19 virus, such as health care workers.
A Johnson & Johnson booster is also under review.
The time frame for a second dose currently remains unclear. Johnson & Johnson recommended a second shot after from 2 to 6 months after the first shot, but data are insufficient to pinpoint the best time.
However, a second dose may be beneficial.