While the omicron variant appears to be more resistant to COVID-19 vaccines, Dr. Anthony Fauci stressed Wednesday that the vaccines still offer substantial protection against the newly-discovered variant.

Fauci also urged Americans not to wait for omicron-specific shots and seek out vaccinations — whether first-time shots or booster shots — as soon as possible.

"Our booster vaccine regimens work against omicron," Fauci said Wednesday during a White House COVID-19 response team briefing. "At this point, there is no need for a variant-specific booster. And so the message remains clear. If you're unvaccinated, get vaccinated. And particularly in the arena of omicron, if you're fully vaccinated, get your booster shot."

Fauci, a top medical adviser for President Joe Biden, says Pfizer's COVID-19 vaccine and a booster shot is 75% effective against omicron. That's significantly lower than the vaccine's effectiveness against other variants, though it still offers significant protection against severe infection.

Pfizer's CEO recently said his company would be able to develop a vaccine within 100 days that's made specifically to fight the omicron variant.

Dr. Rochelle Walensky, the director of the Centers for Disease Control and Prevention, added Wednesday that COVID-19 infections and deaths are on the rise across the country. She noted that the omicron variant represented about 3% of new cases in the U.S. That number is expected to increase in the weeks ahead.