US clears Pfizer and Moderna COVID-19 vaccine boosters for all adults

The US Food and Drug Administration on Friday authorised booster shots of both the Pfizer-BioNTech and Moderna vaccines for all its citizens aged 18-years and above. Pfizer and BioNTech had applied for authorisation last week based on the results of a Phase 3 trial involving more than 10,000 participants aged over 16 years.

The results of the trial showed the booster shots were safe and had an efficacy of 95% against symptomatic COVID-19 compared with the two-dose vaccine schedule in the period when the highly transmissible Delta was the dominant strain. This will make millions of fully vaccinated individuals in the United States eligible for the booster dose. 

Booster doses of the COVID-19 vaccine were previously given to immune-compromised people over 65 years and those at high risk of severe disease and people in high-risk occupations. Both Pfizer-BioNTech and Moderna vaccines are available to people six months after completing their primary series.

Pfizer-BioNTech's vaccine is dosed at 30 micrograms, the same as the primary series, while Moderna's is 50 micrograms, half the primary series. Those people in the US who received the Johnson & Johnson one-dose COVID-19 vaccine were already eligible for a booster of any brand two months after their first shot.

More than 195 million Americans are fully vaccinated, which means they have received two doses of the Pfizer or Moderna vaccines or the single-dose Johnson & Johnson COVID-19 vaccine. More than 30 million Americans have already received a booster dose.