WASHINGTON, United States -- Pfizer announced Tuesday it was seeking US authorization for COVID booster shots among adolescents aged 16 and 17, as concerns grow about the impact of the new Omicron variant.

The Food and Drug Administration (FDA) has so far only granted emergency use authorizations (EUAs) for boosters to people aged 18 and over, six months after their primary series of the Pfizer or Moderna COVID vaccine, or two months after the Johnson & Johnson shot.

''Today, we submitted a request to the @US_FDA to expand the emergency use authorization of a booster dose of our COVID-19 vaccine to include 16- and 17-year-olds,'' Pfizer CEO Albert Bourla wrote on Twitter.

''It is our hope to provide strong protection for as many people as possible, particularly in light of the new variant.''

Experts are concerned that the pattern of mutations detected on the Omicron variant will mean that the protection generated by the current generation of vaccines may take a partial hit.

While lab data should be available to confirm or refute that hypothesis within a matter of weeks, US health authorities are urging all adults to get boosted when they are eligible, so that they will at least be protected against severe COVID, even if not infection itself.

Although more than 200 cases of Omicron have been found in well over a dozen countries, none have so far been detected in the United States, where Delta accounts for more than 99 percent of all infections.

Not all health experts are on board with boosting healthy teens, who are at much lower risk of developing severe COVID but -- in the case of males -- at far higher risk of vaccine-linked myocarditis, when vaccinated with the Pfizer or Moderna messenger RNA vaccines.

''If the FDA takes this action, it will be a total gamble,'' tweeted Vinay Prasad, a hematologist-oncologist at the University of San Francisco with expertise in biostatistics and epidemiology.