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Coronavirus infections are back on the rise in Los Angeles County with a 40% increase in cases over the past week, officials said Thursday.

Local health officials have been continuing to monitor community-wide indicators for early alerts that transmission and risk may be increasing. And although the county remains at a “low concern” level this week, many metrics are trending in the wrong direction, the Public Health Department said Friday.

The weekly case rate is now 126 new cases per 100,000 residents, meaning the county is again experiencing a high rate of transmission for the first time since early March.

Hospitalizations are also slowly beginning to rise, Public Health Director Barbara Ferrer said, and although the numbers remain relatively low, they are increasing each day, with 253 people hospitalized with the virus Friday.

With L.A. County experiencing a high rate of transmission and cases steadily rising, the department encouraged residents to use caution to avoid getting infected with COVID-19 and transmitting it to others.  

“During this period of high transmission and the potential for more infectious variants, one of the best and easiest safety measures is to wear a well-fitting, high filtration mask or respirator when indoors around others,” Ferrer said. “With cases on the rise, the potential for more contagious variants, and lots of opportunities to be exposed, this is a great time to make a choice to get vaccinated or boosted and to wear a mask or respirator when indoors around others.”

The highly contagious omicron BA.2 subvariant is now the predominant strain and was identified in 88% of recent L.A. County samples.

Nationally, the BA.2 subvariant is also the predominant lineage, with 68% of sequenced samples being of that strain for the week ending April 2, the Centers for Disease Control and Prevention estimated.

Another subvariant, called BA.2.12.1, is also on the rise in the U.S., accounting for approximately 29% of sequenced samples for the same week. The new subvariant is estimated to be 20-30% more transmissible than BA.2, and it could quickly become the nation’s dominant strain, health officials said.

In L.A. County, 7% of sequenced samples were identified as BA.2.12.1 for the week ending April 9, up from 3% for the prior week. The California Department of Public Health estimated that BA.2.12.1 will account for 50% of positive cases in the state within a few days. 

Schools in the county also saw an uptick in COVID-19 cases following the spring break and holidays. Among 529,000 coronavirus tests administered last week, 1,842 turned out to be positive for the virus. That’s an increase from the 844 positive tests that showed up the week that ended on April 8, officials said.

While masks are no longer required indoors at schools, health authorities continue to strongly recommend them — particularly for younger children who are not vaccinated and as the highly contagious BA.2 omicron subvariant circulates.

While not yet a cause for significant concern, outbreaks at skilled nursing facilities and sites serving the homeless have recently started to rise as well, health officials said.