The Food and Drug Administration on Friday authorised booster shots of both the Pfizer-BioNTech and Moderna vaccines for everyone 18 and older, opening up eligibility to tens of millions more fully vaccinated adults.

The move simplifies eligibility, fulfills a pledge by President Biden to offer the shots to every American adult and formally allows a practice already in place in at least 10 states.

Fearful that waning protection and the onset of winter will set off a wave of breakthrough infections, a growing number of governors had already offered boosters to everyone 18 and older ahead of the holidays.

Dr Peter Marks, who leads the FDA division that regulates vaccines, said in a statement that “the currently available data support” such an expansion.

He added: “Streamlining the eligibility criteria and making booster doses available to all individuals 18 years of age and older will also help to eliminate confusion about who may receive a booster dose and ensure booster doses are available to all who may need one.”

Dr Anthony S. Fauci, the federal government’s top infectious disease expert, has argued relentlessly over the past month for booster shots for all adults, a position shared by most of Biden’s other health advisers.

Public health experts who argue that healthy younger adults do not need them, he has said, are ignoring the risks of symptomatic Covid-19.

“Enough is enough. Let’s get moving on here,” he said at an event Wednesday night.

If the Centers for Disease Control and Prevention agrees, all adults who received a second shot of either Pfizer or Moderna at least six months ago will most likely be able to get a booster shot by the weekend.

At a White House briefing on Wednesday, Dr Rochelle Walensky, the CDC director, promised that the agency would “quickly review the safety and effectiveness data and make recommendations”.

New York Times News Service