The United States Food and Drug Administration has approved a second booster dose of the Pfizer-BioNTech and the Moderna COVID-19 vaccines for adults ages 50 and above.

The FDA made the announcement on Tuesday, noting its previously authorised single booster dose for immunocompromised individuals after three-dose primary vaccination series was completed.

“Today, the U.S. Food and Drug Administration authorized a second booster dose of either the Pfizer-BioNTech or the Moderna COVID-19 vaccines for older people and certain immunocompromised individuals,” The health body said in a statement.  

The new approval follows data that indicated dropping COVID-19 vaccine protection in older and immunocompromised individuals. 

Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, said the second dose of the vaccines would bolster immunity levels for older and immunocompromised individuals.

“Additionally, the data show that an initial booster dose is critical in helping to protect all adults from the potentially severe outcomes of COVID-19,” Mr Marks said. 

According to data from the Center for Disease Control and Prevention, the number of people who’ve collected their first booster shot remains low in the United States, and less than 50 per cent of people eligible to receive the booster shot have not.