Centers for Disease Control and Prevention Director Dr. Rochelle Walensky and Dr. Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases, both said at a White House briefing on Wednesday that it's too early to consider such a mandate.
Walensky said 32 million people in the United States have already received one of the two available vaccines, and predicted that many more will follow.
Fauci added that there aren't enough doses of either vaccine yet to require inoculations for everyone. He also said he doesn't think a mandate will be necessary.
Walensky and Fauci are top members of Biden's White House COVID-19 Response Team, which gives public updates on the federal response about three times a week.
Both were noncommittal when asked whether it's safer for Americans to wear two masks when they're in public.
Fauci said that science, so far, is inconclusive about whether two masks are better than one and added that he doesn't expect a federal recommendation for Americans to double up.
Walensky said the CDC is "actively looking into" the question, but noted that most people become infected because they don't wear a mask, at all.
White House coronavirus coordinator Jeff Zients said at Wednesday's briefing that the administration has decided to open community vaccination sites in California, at the Oakland Coliseum in the San Francisco Bay Area and the campus of California State University in Los Angeles.
Coronavirus cases have risen across the state in recent weeks and months.
Zients said the plans are part of the administration's aim to establish community vaccination centers nationwide to make inoculation convenient and efficient. He also said mobile vaccination units are coming soon.