▶ Watch Video: Dr. Fauci on potential winter surge as COVID cases in U.S. rise nearly 30% over past two weeks

As COVID-19 cases rise nationwide, Dr. Anthony Fauci is urging Americans to get vaccinated or boosted before traveling and gathering with their families for Thanksgiving. 

“We’ve got to be careful,” he told “CBS Mornings” in an interview Monday.

The warning comes as the seven-day average of new coronavirus infections tops 92,000, a nearly 30% increase in just two weeks, according to the U.S. Centers for Disease Control and Prevention. Hospitalization rates are also starting to climb, raising concerns about a potential new wave of infections during the holiday season

The best way to avoid that scenario is to get vaccinated, Fauci said. 

“As you go into the colder weather, as you go into a season where people travel, where people congregate, and you have a [COVID-19 variant] as transmissible as Delta, you have an issue if you’re not vaccinated,” he said.

Fauci — the director of the National Institute of Allergy and Infectious Diseases, who also serves as President Biden’s chief medical adviser — urged the 60 million Americans who are eligible to be vaccinated but still haven’t gotten a single shot to do so before the holiday gatherings begin.

But he also encouraged fully vaccinated adults to get a booster shot now that the CDC has endorsed vaccine boosters for people 18 and older. In an updated guidance on Friday, the agency said Pfizer and Moderna vaccine recipients, especially those 50 and older, can get a third dose six months after their second shot. Adults who received Johnson & Johnson’s COVID-19 vaccine can already get a booster two months after their first dose. 

Fauci said the definition of “fully vaccinated” has not changed and still reflects those who have received their initial single-dose J&J vaccine or a two-dose regimen of Pfizer’s or Moderna’s vaccine. But he said it’s “entirely conceivable” that the government may ultimately change the definition of “fully vaccinated” to include a booster shot. 

“We will move on this data when we get it,” Fauci said, noting that “boosting individuals dramatically increases the level of protection.”

Fauci also said it’s too early to talk about the idea of herd immunity because protection from COVID-19 wanes for the vaccinated and those who had the virus and recovered.

“Rather than worry about that now and confusing people, just get boosted if you’re vaccinated,” he said.