COVID-19 vaccine booster doses are not necessary right now based on the current evidence, international public health experts — including two FDA vaccine leaders who are leaving the agency this year — wrote a new paper in The Lancet.

Why it matters: The paper is a rebuke of the Biden administration's push to open up booster shots for everyone.

What they're saying: "Even if boosting were eventually shown to decrease the medium-term risk of serious disease, current vaccine supplies could save more lives if used in previously unvaccinated populations than if used as boosters in vaccinated populations," the scientists wrote.

• They did say booster doses could be appropriate for immunocompromised people, and indeed that population can get a third dose of an mRNA vaccine.

The bottom line: Medical ethicists and scientists have not supported widespread booster shots, as the vaccines are still extremely effective in preventing severe COVID-19 and death, and considering a majority of the world still hasn't gotten one shot.