WASHINGTON (NewsNation Now) — President Joe Biden delivered remarks Tuesday on the spread of the omicron COVID-19 variant across the country amid fears of a post-holiday surge.

“If you are vaccinated and boosted, you are highly protected,” he said. “You know, be concerned about omicron, but don’t be alarmed. If you are unvaccinated, you have some reason to be alarmed.”

Scientists say omicron spreads even easier than other coronavirus strains, including delta. The variant had already become the dominant strain in the U.S shortly before Americans celebrated the holidays and the New Year.

“You can still get COVID, but it’s highly unlikely, very unlikely, that you’ll become seriously ill,” Biden said of vaccinated people.

“There is no excuse for anyone being unvaccinated,” Biden continued. “This continues to be a pandemic of the unvaccinated.”

Biden also announced that the U.S. is doubling its order for an anti-viral pill produced by Pfizer that was recently authorized by the FDA to prevent serious illness and death from COVID-19. 

Last month, Biden announced 500 million free rapid tests would be shipped to Americans. The December announcement marked a major shift for Biden, whose earlier plan had called for many Americans to purchase the hard-to-find tests on their own and then seek reimbursement from their health insurance. Public health experts had criticized Biden’s initial approach as unwieldy and warned that the U.S. would face another round of problems with testing at a critical time.

The outbreak from this latest strain of the coronavirus has required the federal government to get more aggressive in addressing the likely wave of infections, but Biden promised a weary nation that there would not be a mass lockdown of schools or businesses.

“I know you’re tired, and I know you’re frustrated. We all want this to be over. But we’re still in it,” Biden said last month. “We also have more tools than we had before. We’re ready, we’ll get through this.”

Former U.S. Surgeon General Jerome Adams said on “Morning in America” last month that while omicron was sweeping across the nation, this was not the last we have seen of the delta variant.

“People really need to understand is we’re still going to see this delta surge filling up hospitals for another two to three weeks, we’re gonna see it run the course. Then any cases of omicron that end up in the hospital on top of that really could be the straw that breaks the camel’s back,” Adams said. “And then people won’t be able to get care for heart attacks, or strokes, or car wrecks.”

Biden’s remarks come as some government agencies updated their safety measures to prevent widespread infection. In Chicago, anyone 5 years and older will be required to show proof of vaccination to dine indoors, visit gyms or enter entertainment venues where food or drinks are being served. Boston introduced similar guidelines Monday as well.

Early studies suggest that the vaccinated will need a booster shot for the best chance at preventing an omicron infection but that even without the extra dose, vaccination should still largely protect people from serious sickness or death.

About 33% of all Americans have received their booster shot, according to data to compiled by the Centers for Disease Control and Prevention. More than 62% of the population is considered fully vaccinated, according to CDC data.