While the winter surge of COVID-19 infections fueled by the omicron variant appears to be easing, authorities are watching the emergence of an omicron “sub-lineage” that has spread rapidly in some countries, with Los Angeles County’s health director saying today four cases have been found locally.

Barbara Ferrer told reporters in an online briefing that the original omicron variant, technically known as BA.1, remains the dominant variant circulating in Los Angeles County, representing more than 98% of sequenced cases as of early January. But with four cases of the omicron “sub-lineage” known as BA.2 now identified, she said officials will be awaiting answers from researchers about whether it could potentially lead to another surge.

“In places that have already passed their peak of omicron cases, it does appear that BA.2 is causing a new surge,” Ferrer said. “In places at their peak of the omicron surge that have significant BA.2 prevalence, it doesn’t appear that BA.2 is behaving dramatically different than other omicron lineages. And compared with other omicron lineages, BA.2 does not really have many unique mutations that would be impacting the part of the virus that’s targeted by our immune system.”

Ferrer said it’s too early to sound any alarms over the BA.2 variant, since too many questions about its impact still need to be answered, but it should serve as a reminder to people that more COVID-19 variants could develop as long as the virus continues to spread. And that means continued adherence to infection-control measures—and vaccinations.

“Getting as many people vaccinated as soon as possible can help us sustain the declines we’re seeing and limit opportunities in the future for new variants to arise,” she said.

Ferrer noted again that the county is seeing declines in case rates and hospitalizations, indicating the peak of the omicron case surge has passed.

Ferrer noted that COVID-19 deaths remain relatively high, averaging about 59 per day in the county. On Thursday, the county reported 85 new virus-related deaths, while Long Beach reported another two deaths.

Another 26,010 new COVID cases were reported Thursday, and the rolling daily average rate of people testing positive for the virus fell to 12.7%, down from around 20% earlier this month.

Long Beach reported 828 news cases, with its testing positivity rate falling slightly to 25.4% from a high of nearly 30% 10 days ago.

According to state figures, there were 4,323 COVID-positive patients in county hospitals as of Thursday, down from 4,534 on Wednesday. The number of those patients being treated in intensive care was 746, a drop from 780 a day earlier.

According to the county, 81% of eligible county residents aged 5 and above have received at least one dose of vaccine, and 72% are fully vaccinated.

Only 32% are fully vaccinated with a booster shot. Of the county’s overall 10.3million population, 77% have received one dose, 69% are fully vaccinated, and 31% are vaccinated and boosted.

The vaccination rate among children aged 5-11 remains low, with only 31% having received at least one dose, and only 21% fully vaccinated. Ferrer said the low vaccination rate among children “creates significant vulnerability for spread” of the virus.

Of the more than 6.5 million fully vaccinated residents in the county, 580,942 have subsequently gotten infected with COVID, for a rate of 8.9%.

That’s a notably higher rate than December, when it was 2%, an increase Ferrer attributed to the highly transmissible omicron variant. But the number of fully vaccinated residents who have been hospitalized was 6,998 as of this month, fora rate of 0.1%. The number who have died is 886, for a rate of 0.01%.