Moderna COVID-19 vaccine
Moderna COVID-19 vaccineReuters

A panel of expert advisers to the US Food and Drug Administration (FDA) unanimously voted on Thursday to recommend booster shots of Moderna's COVID-19 vaccine for Americans aged 65 and older and those at high risk of severe illness or occupational exposure to the virus, Reuters reports.

If the FDA signs off on Moderna's booster, the US Centers for Disease Control and Prevention (CDC) will make specific recommendations on who should get the shots. CDC advisers are scheduled to meet next week.

The FDA's Vaccines and Related Biological Products Advisory Committee met on Thursday to consider the additional dose of the Moderna vaccine and will weigh whether to make a similar recommendation for Johnson & Johnson's vaccine on Friday.

The vote to back Moderna's booster was 19-0.

Last month, the FDA authorized a booster dose of the Pfizer and BioNTech vaccine for older adults and some Americans at high-risk of illness.

Thursday’s vote came two days after FDA staff said in documents that data for Moderna's vaccine showed that the booster does increase protective antibodies.

But they also said the difference in antibody levels before and after the shot was not wide enough by one measure of success specified by the FDA, particularly in those whose antibody levels had remained high.