Dr. Anthony Fauci said Wednesday he believes it’s only a matter of time before the definition of “fully vaccinated” includes having a COVID-19 booster shot amid the spread of the worrisome omicron variant of the virus and the ongoing infections linked to the delta strain.
Fauci, the nation’s top infectious disease expert, told CNN that federal health officials were monitoring the threat of mutated strains of the virus on “literally a daily basis,” and that public health guidance can always change amid new surges in infectious.
“My own personal opinion … it’s gonna be a matter of when, not if” the definition of “fully vaccinated” changes, Fauci told CNN’s Kate Bolduan on Wednesday.
His comments came shortly after Pfizer and BioNTech said a two-course regimen of their coronavirus vaccine appeared to be significantly less effective at combating the omicron strain, and that preliminary data showed a booster jab dramatically increased neutralizing antibodies that can fight the virus.
Antibodies are just one way to measure a vaccine’s performance, and scientists are cautiously optimistic that the vaccines approved in the U.S. will still likely protect against severe disease and death associated with COVID-19.
Health officials are racing to understand the threat of the omicron strain, which has spread to dozens of nations around the globe after South Africa said health officials had discovered it last month. Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, said Wednesday that more than 40 people had been diagnosed with the omicron variant in the U.S., but almost all of them were only mildly ill, even the unvaccinated.
Still, COVID-19 cases in America have been rising again for weeks, and the delta variant remains the dominant strain, a troubling statistic even as figures show more than 200 million Americans have now been fully vaccinated against the virus.
“The booster shot could be the answer to the challenge that we’re facing with the omicron,” Fauci said in a separate interview with The Washington Post this week. “So, if ever there was a clarion call for people who are not vaccinated to get vaccinated, and those who are vaccinated fully to get boosted, the new challenge with the omicron variant clearly is that.”
This article originally appeared on HuffPost and has been updated.