US to limit Covid boosters to over-65s or those at high risk

In a letter to the prestigious New England Journal of Medicine, the Food and Drug Administration's Vinayak Prasad and Commissioner Martin Makary said the shift brought US policy more in line with European nations.

They described the initial rollout of Covid-19 vaccines as "a major scientific, medical, and regulatory accomplishment" -- but argued that the benefits of repeated boosters in low-risk individuals remained uncertain.

They contrasted the US approach with that of countries such as the United Kingdom, France and Germany, which limit booster recommendations to older adults and those with underlying conditions.

Going forward, the FDA believes it will continue to find the benefit-risk balance favorable for people over 65, and people over the age of six months with one or more underlying conditions.

However, "for all healthy persons -- those with no risk factors for severe Covid-19 -- between the ages of 6 months and 64 years, the FDA anticipates the need for randomized, controlled trial data," they said.

"The control group could receive a saline placebo."

They identified adults aged 50 to 64 as an ideal study population, and said trials should assess whether boosters reduce symptomatic illness, severe disease, hospitalization, and death.

Makary and Prasad also sought to reassure those worried about losing access to vaccines under the new framework.

The Centers for Disease Control and Prevention's definition of risk factors is "vast, including obesity and even mental health conditions such as depression," they wrote, adding that between 100 million and 200 million Americans would likely still qualify under this guidance.

Prasad, a hematologist-oncologist who now leads the FDA's Center for Biologics Evaluation and Research (CBER), rose to prominence during the pandemic for publicly questioning the widespread use of boosters.