• White House chief medical advisor Dr. Anthony Fauci said the primary two-dose vaccination series from Pfizer and BioNTech is significantly compromised by omicron.
• However, two shots still offer considerable protection against severe disease, he said.
• A booster dose increases protection against symptomatic disease to 75%, Fauci said.

White House chief medical advisor Dr. Anthony Fauci said Wednesday that currently available booster shots work against the omicron variant of Covid-19 and do not need to be adjusted to fight the new, highly contagious strain of the virus at this time.

"Our booster vaccine regimens work against omicron," Fauci told the public during a White House Covid update on Wednesday. "At this point, there is no need for a variant-specific booster."

Fauci said the primary two-dose vaccination series from Pfizer and BioNTech is significantly compromised by omicron, but still offers considerable protection against severe disease. Protection from the two-dose vaccine against infection dropped to 33% compared with 80% before the emergence of omicron. However, two doses are still 70% effective at preventing hospitalization in omicron patients in South Africa, Fauci said.

"Obviously, this is significantly down but there is the maintaining of a degree of protection against hospitalization," Fauci said.

A booster dose increases protection against symptomatic disease to 75%, Fauci said, citing data from the U.K. Health Security Agency.

"And so the message remains clear. If you are unvaccinated get vaccinated, and particularly in the arena of omicron if you are fully vaccinated, get your booster shot," Fauci said.

The unvaccinated are eight times more likely to end up in the hospital and 14 times more likely to die compared with people who are fully vaccinated, said White House Covid response coordinator Jeff Zients, citing data from the U.S. Centers for Disease Control and Prevention.

CDC Director Rochelle Walensky said 36 states have detected omicron so far, and the variant makes up about 3% of Covid cases nationwide. However, omicron infections are likely much higher in New York and New Jersey, she said, making up about 13% of cases.

"Early data suggests that omicron is more transmissible than delta with a doubling time of about two days," Walensky said.

Sixty-one percent of Americans are fully vaccinated against Covid and 27% of them have received a booster shot, according to CDC data.

About 68,000 Americans are hospitalized with Covid-19, according to a seven-day average of Department of Health and Human Services data as of Tuesday, up 9% over the previous week and 21% over the last two weeks.

Correction: About 68,000 Americans are hospitalized with Covid-19, according to a seven-day average of Department of Health and Human Services data as of Tuesday. An earlier version misstated the day.