US greenlights Pfizer and Moderna booster shots for those 18 and older

WASHINGTON • The United States authorised the Pfizer and Moderna Covid-19 vaccine boosters for all people aged 18 and older, as the world's hardest-hit country enters a winter wave of the pandemic.

Boosters were previously available to the immunocompromised, people over 65, those at high risk of severe disease, and people in high-risk occupations.

The new decision "helps to provide continued protection against Covid-19, including the serious consequences that can occur, such as hospitalisation and death", said Dr Janet Woodcock, acting commissioner of the Food and Drug Administration (FDA).

US Centres for Disease Control and Prevention (CDC) director Rochelle Walensky formally signed off on the recommendations, stating that boosters "are an important public health tool to strengthen our defences against the virus as we enter the winter holidays".

The FDA said it based its decision on data demonstrating a strong immune response to boosters from hundreds of people dosed with both brands of vaccines.

Pfizer also carried out a clinical trial involving 10,000 people aged over 16 which found that the boosters showed an efficacy against symptomatic infection of over 95 per cent compared with when people did not receive a booster.

Both vaccines are available to people six months after completing their primary series.

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

The booster decision comes as cases are rapidly rising in the US, reaching 88,000 new infections a day on average as the country enters its fifth wave.

The US is officially the pandemic's hardest-hit country, with more than 760,000 deaths.

Prior to Friday's decision, some experts had expressed misgivings over widening boosters to all adults. Overall, however, US health agencies took the view that the benefits outweigh the risks.

Both Pfizer and Moderna are conducting post-authorisation studies to assess the risks of myocarditis after third shots.

It is also possible that, rather than considering the third dose a booster, the vaccines work optimally when administered three times, something that will become clearer over time as data accrues.

AGENCE FRANCE-PRESSE