(CNN) Pfizer is expected to seek authorization from the US Food and Drug Administration for its vaccine booster shot for those who are ages 16 and 17, a source familiar with the plan told CNN on Monday.
Currently only those 18 and up are eligible for booster shots six months after their second dose of the Pfizer vaccine.
Pfizer didn't immediately respond to CNN's request for comment.
The development comes as scientists in the US and around the world are racing to learn more about a new coronavirus variant called Omicron. President Joe Biden urged Americans earlier Monday not to panic over the new variant, and encouraged those who have not yet gotten a booster but are eligible to do so.
"We have the best vaccine in the world, the best medicines, the best scientists, and we're learning more every single day. And we'll fight this variant with scientific and knowledgeable actions and speed -- not chaos and confusion," the President said.
Biden had hoped to have boosters made widely available months ago, but emergency booster authorization ultimately didn't happen until October, and widespread booster shots have not been available until this month. Asked on Monday if making boosters available to everyone sooner could have helped with the current dynamic, press secretary Jen Psaki referred the question to medical experts.
In a sign of the potential threat from Omicron, the US Centers for Disease Control and Prevention strengthened its recommendations for booster shots earlier Monday, saying all adults should get boosted six months after the second dose of Pfizer's or Moderna's vaccine or two months after the single-dose Johnson & Johnson vaccine.
"Today, CDC is strengthening its recommendation on booster doses for individuals who are 18 years and older," CDC Director Dr. Rochelle Walensky said in a statement. "The recent emergence of the Omicron variant (B.1.1.529) further emphasizes the importance of vaccination, boosters, and prevention efforts needed to protect against COVID-19," she added.
Previously, the CDC had said people should get boosters if they are 50 and older, or 18 and older and living in long-term care facilities. Otherwise, it advised that anyone 18 and older may get a booster. Now the word "should" applies to everyone 18 and older.
Dr. Anthony Fauci, the nation's leading infectious disease expert, said Sunday that hopefully scientists will be able to determine soon whether the Omicron variant is resistant to current Covid-19 vaccines. Fauci said he doesn't think it's possible that Omicron could completely evade the vaccines' protection but that it may diminish the level of protection.
This story has been updated with additional information Monday.