The specter of a new COVID wave caused by yet another mutation of the coronavirus is troubling. But according to the White House’s top medical adviser, Dr. Anthony Fauci, the spread of stealth Omicron likely won’t be as disastrous as previous waves.

Is stealth Omicron more contagious?

On Sunday, Fauci told ABC’s This Week that the subvariant was between 50% and 60% more transmissible than original Omicron—which was already the most virulent form of COVID yet.

“The bottom line is we’ll likely see an uptick in cases, as we’ve seen in the European countries, particularly the U.K.,” Fauci said, adding that he doesn’t think an “uptick” will evolve into a full-blown “surge.”

The stealth Omicron subvariant has already become the dominant form of COVID worldwide, the World Health Organization (WHO) says, accounting for 86% of all COVID infections in the past month. But in the U.S., stealth Omicron accounts only for roughly 30% of total new cases, which means the subvariant still has room for growth.

But greater virulence does not necessarily mean stealth Omicron is more dangerous than Omicron.

“When you look at the cases they do not appear to be any more severe [than Omicron] and they do not appear to evade immune responses either from vaccine or prior infection,” Fauci said.

How can we prevent a surge in COVID?

The U.S. is in a somewhat better place than other countries when it comes to fending against stealth Omicron, partly because of how badly the country suffered previous waves.

According to the CDC, roughly 95% of the U.S. population over the age of 16 has developed antibodies against COVID, due to a combination of vaccination and prior infection. That leaves U.S. adults with an adequate level of immunity against severe infection, although children remain vulnerable.

“Only 65% of the total population has been vaccinated, and of those who are eligible for a booster only 50% of them have been boosted,” Fauci said on Sunday.

Continuing to increase vaccination rates—and booster rates among those eligible—is “the easiest way to prevent” a surge in stealth Omicron cases, Fauci said.

Do we need to reimpose restrictions?

The U.S. has been rolling back restrictions on mask mandates and “vaccine passports” for months, as the country begins to learn how to live with the virus.

The earlier relaxation of COVID restrictions might actually contribute to the U.S. avoiding a “surge” in stealth Omicron cases, as places like the U.K. have seen.

In the U.K., the relaxation of social distancing measures coincided with the arrival of stealth Omicron, and the dramatic change in public behavior helped the virus spread. The U.S. is unlikely to experience a similar large-scale change in behavior.

According to the CDC, 98% of people in the U.S. are already living in areas where masks are no longer required indoors. Fauci says he doesn’t expect stealth Omicron’s arrival in the U.S. will result in the country “going back into any kind of strict restrictions.”

However, Fauci warned that the U.S. needs to maintain flexible prevention policies and that the current lull in cases—U.S. daily COVID cases and deaths are in decline—is not an excuse for idleness.

“There are a lot of things we can do from a public health standpoint,” Fauci told ABC, advising the government to continue stockpiling antiviral medicines and COVID tests to prepare against another wave.

“We just can’t stand still…This virus has fooled us before, and we really must be prepared for the possibility that we might get another variant.”