Coronavirus cases are rising overseas, bringing concerns that California will follow suit despite the decline of reported infections since early January.

According to the World Health Organization’s COVID-19 dashboard, infections are escalating in Europe and Southeast Asia. In the U.K., test positivity rates have increased about 37% the last seven days, as of Monday, due to the BA.2 omicron subvariant. The hike could also be attributed to the roll back of safety measures and waning immunity from vaccines, according to the BBC.

“Over the last year or so, what happens in the U.K. usually happens here a few weeks later,” White House Chief Medical Advisor Dr. Anthony Fauci told NPR. “And right now, the U.K. is seeing somewhat of a rebound in cases.”

Timeline of BA.2 in California

California reported its first cases of BA.2, dubbed the “stealth omicron,” in late January. BA.2 had previously been detected in more than 40 countries, including Sweden, Singapore and the Philippines, as well as other states in the U.S.

This came after the original omicron variant was skyrocketing cases in the state, following the winter holidays.

The Centers for Disease Control and Prevention’s estimates of variant proportions from the end of January to Feb. 19 show omicron was the dominant variant of the coronavirus at that time.

Among the COVID specimens tested in California, 98% were from the omicron variant. BA.2 represented 1.8% of the variants and delta 0.15%.

Within a few weeks, cases with the BA.2 variant grew.

From March 13 to March 19, in the region that includes California, Nevada, Arizona, and some U.S. territories, BA.2 was estimated to make up 41.3% and the original omicron 58.7%. Nationally, BA.2 is estimated to make up 34.9%.

Initially, the WHO classified omicron as a variant of concern on Nov. 26, 2021. With the rise of the subvariant, the organization announced on Feb. 22 that the BA.2 will also continue to be considered as a variant of concern, as it is a sublineage of omicron.

Health officials are now warning that the omicron subvariant could soon drive cases back up this spring.

What’s the difference between omicron and BA.2?

According to the CDC, the COVID virus is constantly changing and mutating, subsequently creating new variants.

Between omicron and BA.2, main differences lie in its genetic sequence. According to the WHO, the omicron subvariant is more transmissible, but the differences in transmissibility between the two is less than that seen with omicron and delta. Studies on risk of reinfection are ongoing.


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