▶ Watch Video: Health officials say Americans should stay vigilant as COVID cases rise, Omicron continues to spread

As the COVID-19 Omicron variant continues to surge across the U.S., Dr. Anthony Fauci says officials should “seriously” consider implementing a vaccine requirement for domestic flights. 

“There’s requirements that you might want to get if you want to get into college, or you want to go to a university, or you want to work in certain places,” Fauci, the president’s chief medical adviser, said on MSNBC on Monday. “When you make vaccination a requirement, that’s another incentive to get more people vaccinated. If you want to do that with domestic flights, I think that’s something that seriously should be considered.”

The U.S. already requires foreign visitors to show proof of vaccination to board an international flight to the United States, but there is no such rule for domestic travelers. 

The highly contagious Omicron variant of COVID-19 has fueled a rising wave of infections across the U.S. and caused significant disruptions to holiday travel. From Friday to Monday, more than 5,400 flights in the U.S. were canceled and thousands more were delayed, with airlines citing staff shortages caused by COVID infections among pilots, crew and other airline workers out sick.

Omicron was first identified around Thanksgiving and rapidly overtook Delta as the dominant strain in the U.S. As Fauci said on the Monday broadcast, “Omicron is different.” 

“It has extraordinary capability of transmitting very efficiently from person to person,” he said. “…We really still need to be extremely careful getting people vaccinated, getting people boosted, making sure we wear masks. We’re in a tough situation with Omicron. It’s not something to be taken lightly.” 

Less than 62% of the U.S. population and 71% of those over the age of 12 are fully vaccinated, and only about a third of vaccinated people have received their booster dose, according to the latest data from the CDC.  

Fauci said Monday that while studies suggest “severity of the disease is less” with Omicron, he and other health professionals remain concerned about the variant’s impact on those who are unvaccinated.

“Even if this virus is inherently less severe, just the volume of the numbers of cases that we’re gonna have could actually put a stress on the hospital system,” he said. Many communities in the U.S. have seen such a stress in recent weeks as ICU beds fill up and medical staff is stretched dangerously thin.