Moderna asks US FDA for authorisation for a second Covid-19 booster for all adults

NEW YORK (NYTIMES) - Moderna said late on Thursday (March 17) that it asked the Food and Drug Administration (FDA) for emergency authorisation of a second booster of its coronavirus vaccine for all adults, a significantly broader request than Pfizer and BioNTech filed for their shot this week.

The request is likely to intensify the latest round of an ongoing scientific debate over how long protection from the two most-used vaccines in the United States lasts in the face of new variants.

On Tuesday, Pfizer and its German partner, BioNTech, asked for emergency authorisation for a second booster for those aged 65 and older.

The request was based heavily on data from Israel, where such shots are authorised for a somewhat broader group.

Federal health officials have said they are concerned about waning potency of the booster shot that was authorised for Moderna and Pfizer in the fall.

Although there are indications that regulators could move swiftly on Pfizer's request, it is unclear how favourably they will view Moderna's more sweeping application.

Moderna said its request covered all adults, so the Centres for Disease Control and Prevention (CDC) and healthcare providers could determine the appropriate use of a second booster, including for those at higher risk of Covid-19 disease because of age or underlying medical conditions.

Pfizer said its request was partly based on recent data on how well its vaccine protected against the Omicron variant in the US and Israel.

Scientists are sharply divided over whether another dose is necessary now and, if so, for whom.

"I'm a strong proponent of giving a second booster now," said Dr Peter Hotez, a vaccine expert at the Baylor College of Medicine in Houston.

He said the first booster shot had "made a huge difference" in bolstering protection against hospitalisation and even infection from the Omicron variant.

"It's also clear that protection is waning now pretty quickly a few months after your third dose," he said. "So it's short-lived. The hope is that a second booster would restore it."

But Dr Jesse Goodman, a former chief scientist for the FDA, said: "While protection is waning against mild infections, without more information, we do not yet know to what extent, if any, protection is waning against severe disease."

Nor is it clear, he said, "to what degree and for how long another booster might help".

Among the data the companies cited was a study released last month by the CDC that found the effectiveness of Pfizer's and Moderna's vaccines against hospitalisation dropped from 91 per cent two months after a booster shot to 78 per cent after four months.

The study presented a broad snapshot; it did not break down hospitalisations by age, the presence of underlying conditions or other factors.