There could be another COVID surge soon if Americans get complacent ahead of the holidays, the nation’s leading infectious disease expert warned on Sunday.

Dr. Anthony Fauci issued the warning to Americans during an interview with “Face the Nation,” saying, “If you look at the history ... of the different surges we've had, it's come up, start to come down and then all of a sudden boom, come back up again.

“As it's coming down, we have within our capability, we can make this happen. Namely go down to a very, very low level, with vaccination and with mitigation,” he said.

Fauci said it is “just too soon to tell” whether holiday gatherings would need to be limited again this year due to the pandemic, but he told “Face the Nation” that Americans need to stay focused on lowering the number of new COVID infections and hospitalizations.

He continued, “We've just got to concentrate on continuing to get those numbers down and not try to jump ahead by weeks or months and say what we're going to do at a particular time. Let’s focus like a laser on continuing to get those cases down. And we can do it by people getting vaccinated and also in the situation where boosters are appropriate to get people boosted.”

Fauci’s hesitancy to give the green light on holiday family gatherings comes as the U.S. hit the dire milestone of 700,000 COVID-19 deaths last week as new cases of the virus surge, reaching over 43.6 million, according to data from Johns Hopkins University.

Fauci has urged Americans to get vaccinated to help the U.S. return to a sense of normalcy, without giving a recent indication of what percentage of the country would need to be fully vaccinated against COVID-19 to reach immunity.

According to the Centers for Disease Control and Prevention, over 185 million Americans are fully vaccinated against the virus, accounting for 55.9% of the population.

Only people who are 12 and older are eligible to receive the COVID vaccine. Pfizer has applied for authorization of a vaccine that would be administered to kids aged 5 to 11 that is expected to be approved in October. Both the Moderna and Johnson & Johnson COVID vaccines are authorized for use with people who are 18 and older.

On Oct. 1, the CDC also issued recommendations for holiday celebrations, suggesting avoiding indoor gatherings this holiday season in favor of virtual or socially distanced outdoor gatherings. For those events held indoors, it proposed using a window for enhanced circulation or opening windows and doors to “bring in fresh air” if possible.

Fauci also agreed with the CDC’s recommendation for added ventilation, telling “Face the Nation,” “What we should be doing is look at ventilation in indoor places. When you have something spread by aerosol, you absolutely want more ventilation, which is the reason why outdoors is always much safer than indoors.”

anthony fauci Top U.S. pandemic advisor Anthony Fauci is pictured. Photo: AFP / SAUL LOEB