Mirroring trends seen across the country, Los Angeles County is seeing an increase in the ratio of coronavirus cases turning out to be the highly contagious omicron subvariant, BA.2.

Here’s what to know about the variant:

What is BA.2?

BA.2, sometimes referred to as “stealth omicron,” is considered a subvariant of omicron.

It has become the dominant variant of the coronavirus around the world, the World Health Organization announced earlier this month.

BA.2 is believed to be driving an increase in COVID-19 cases in several countries, including in much of Europe. Now, there are worries that the variant may soon push cases up in the U.S. too.

The subvariant has mutations in its spike protein that makes it different from BA.1, which has been the most common omicron sublineage reported in the U.S. and the one believed to be behind the record-setting high case numbers during the winter surge.

The nation’s top infectious disease expert, Dr. Anthony Fauci, has said that the subvariant is considered 50-60% more transmissible than the previous version.

Is BA.2 more dangerous?

BA.2 is known to be more highly contagious than earlier variants, though it does not appear to be more severe than other versions of the virus, health authorities say.

Is it spreading?

While COVID-19 case numbers are still declining in the U.S., BA.2 is accounting for a larger percentage of those cases.

BA.2 accounted for about 35% of samples sequenced between March 13 and March 19, up from 22.3% the week before, according to the U.S. Centers for Disease Control and Prevention.

The week before that, BA.2 was found in 12.6% of sequenced cases.

Since fewer people are getting tested post-surge, and not every sample is sequenced, there could be more BA.2 infections that documented.

How’s L.A. County doing?

The ratio of samples turning out to be the BA.2 subvariant has been increasing in Los Angeles County, just like the rest of the country.

Between February 27 and March 5, 14.7% of sequenced cases in L.A. County were found to be BA.2, the L.A. County Department of Public Health reported last week.

That is more than double what it was the week before, when BA.2 accounted for 6.4% of sequenced cases in the county.

L.A. County Director of Public Health Barbara Ferrer has said that the increase of BA.2 means that the region needs to be prepared “for the possibility of more cases in the near future.”

“Although most of our metrics continue to improve, the county continues to see substantial transmission,” Ferrer warned Thursday. “Along with the increasing circulation of the more-infectious BA.2 subvariant, everyone, especially those who are at elevated risk or live with someone at elevated risk, should wear a high-quality mask and get vaccinated and boosted.”

While L.A. County’s rate is lower than that of other cities, the numbers are following a similar pattern seen with previous variants that emerged and swiftly spread throughout the region, health authorities said.

L.A. County has eased COVID-19 restrictions in recent weeks, but the health department is still strongly recommending that residents mask up when around others in public.

Is another surge expected?

It’s not yet clear whether BA.2 will fuel another major surge in the U.S., where local, state and federal authorities have been relaxing masking and vaccine verification restrictions in recent weeks.

Fauci has said that he wouldn’t be surprised if case numbers begin to climb in the U.S. in the next few weeks.

But he doesn’t expect another major surge.

“I would not be surprised at all, if we do see somewhat of an uptick,” Fauci told the Washington Post last week. “The extent of it and the degree to which it impacts seriousness of disease like hospitalizations and death remains to be seen. I don’t really see, unless something changes dramatically, that there would be a major surge.”