By Julia Marnin

As mask mandates lift in most states and coronavirus cases continue to drop, the “stealth” omicron subvariant, BA.2, is becoming more prevalent in the United States.

But what does this mean and is it a reason to worry amid easing virus restrictions?

Cases of this particular omicron subvariant, one of a few, keep popping up and have roughly doubled the past few weeks in the U.S., according to Centers for Disease Control and Prevention data estimates. It now makes up 11.6% of overall virus cases as of March 5 since it began doubling as of Feb. 5.

“All in all, I think we’re really gonna be okay and I don’t think BA.2 is gonna be problematic like omicron,” said Dr. Thomas Russo, an infectious disease doctor and professor and chief of the Division of Infectious Diseases at the University of Buffalo. He referenced the omicron COVID-19 wave that hit after its discovery in November.

In some parts of the world, the BA.2 subvariant has replaced the original omicron strain, known as BA.1, as the most dominant even as global cases go down, the World Health Organization said in a March 8 statement.

Russo said BA.2 is “probably about 30% more infectious than BA.1” but that it’s believed to be less virulent based on currently available data.

“It looks like our vaccines are gonna hold up against BA.2 in a similar fashion, as they’ve held up with BA.1,” he added. He acknowledged that with the original omicron strain, vaccines can be “imperfect at preventing infection” and there’s a better chance of prevention depending on whether someone is up to date on their shots.

However, he said vaccines are “really pretty good at preventing severe disease and hospitalizations” with omicron and he thinks that will be the same for BA.2.

The doubling of BA.2 cases in the U.S. comes as the CDC forecasts new daily COVID-19 hospital admissions “will likely decrease” for the month, it said as of March 7.

A recent study from Denmark found that after a BA.1 infection, it’s possible to get reinfected with BA.2, but it’s a rare occurrence.

These reinfections were found “mostly in young unvaccinated individuals with mild disease” that didn’t result in “hospitalization or death.”

At least 47 Danish people have caught omicron twice from a BA.2 reinfection occurring shortly after a BA.1 infection, according to the research. A “reduced overall viral load” was observed in reinfections in which the BA.2 subvariant was responsible.

Russo said this means the Denmark study indicates that the immunity built up from omicron and vaccination is “probably going to hold up pretty well against BA.2.”

Ultimately, Russo said he doesn’t think that BA.2 is going to result in a COVID-19 surge like with BA.1.

He said that the most at risk of developing severe COVID-19 are the unvaccinated; the immunocompromised; the elderly; those with underlying diseases; and those not up to date on their shots. He advises these groups to be cautious and consider mask wearing until cases get down to even lower levels.

“At this point, there’s no grounds for panic, though we need to keep an eye on it,” he said of BA.2.

He added the best protection is to get vaccinated if you’re unvaccinated and to get a booster shot if you’re not up to date on vaccines.

The WHO said it “will continue to closely monitor the BA.2 lineage as part of Omicron and requests countries to continue to be vigilant, to monitor and report sequences, as well as to conduct independent and comparative analyses of the different Omicron sublineages,” in a Feb. 22 statement.

In the U.S., masking up while indoors in public isn’t recommended in more than 90% of the country as of March 3, since most people live in a location with a low or medium COVID-19 community level, according to the CDC.

However, experts still advise keeping face masks on hand as well as continuing to wear them in certain circumstances.