New versions of omicron variant gaining ground in US

Omicron COVID-19 subvariants BA.4 and BA.5 represent an increasing number of new infections in the country, according to the Centers for Disease Control and Prevention (CDC), though it’s unclear what the impact will be.

New estimates from the CDC show that for the week ending June 4, the two subvariants combined accounted for 13 percent of all new U.S. cases. That’s an increase from the combined 7.5 percent estimated for the week ending May 28.

During the week ending June 4, BA.5 accounted for an estimated 7.6 percent of cases and BA.4 accounted for 5.4 percent of cases, up from 4.2 percent and 3.3 percent, respectively, the previous week.

There are also regional differences in the rise of the new subvariants. In the southern region comprising Louisiana, Texas, Arkansas, Oklahoma and New Mexico, BA.4 and BA. 5 account for about 22 percent of all infections.

Data on BA.4 and BA.5 is limited, though early evidence suggests they are more infectious and may be able to evade some of the immunity people have acquired from being infected with other variants. There isn’t evidence to show they cause more severe disease.

It’s still unclear what the rise in the new variants means for the trajectory of the U.S. pandemic, though some public health experts think BA.4 and BA.5 will soon become the dominant subvariants and prolong the current wave of infections. The majority of cases right now are being driven by the omicron subvariants BA.2.12.1 and BA.2.

COVID-19 cases have risen in the U.S. to around 100,000 per day, though the real number could be as much as five times higher given that many cases go unreported.