Americans will likely have to get a third shot of the Pfizer and Moderna vaccines, Dr. Anthony Fauci said Thursday at a White House press briefing.
"I must say from my own experience as an immunologist, I would not at all be surprised that the adequate full regimen for vaccination will likely be three doses," Fauci, who is director of the National Institute of Allergy and Infectious Diseases, told reporters.
He said the Food and Drug Administration and the Centers for Disease Control and Prevention would make the final decision.
Whether those who got the one-shot Johnson & Johnson will need boosters remains to be seen.
Any booster for the Pfizer and Moderna vaccines would be given between five and eight months after the second dose.
White House Coronavirus Response Coordinator Jeffrey Zients said that 175 million Americans were now fully vaccinated, an increase of 10 million from a month ago.
"That's a major milestone in our vaccination effort," Zients said at the briefing.
The seven-day rolling average on Thursday of new COVID-19 cases in the U.S. was more than 150,000 per day, while hospitalizations were at 12,000 and deaths at 953, CDC Director Dr. Rochelle Walensky said.
Fauci also addressed the so-called mu variant, which the World Health Organization added to its list of variants of interest Monday.
"We're paying attention to it — we take everything like that seriously — but we don't consider it an immediate threat right now," said Fauci, who also serves as White House chief medical adviser.
First identified in Colombia, mu has been seen in at least 39 countries, WHO said.
Some information for this report came from The Associated Press.