Where BA.2 'Stealth' COVID Variant is Most Prevalent in U.S.

A new subvariant of the Omicron COVID-19 variant is starting to spread in the United States and the East and West coasts of the country are seeing more cases of it than are being seen in the middle of the country.

The BA.2 variant, a subvariant of B.1 which is commonly known as Omicron, was discovered in the United States in January. It accounts for less than 5 percent of cases in the United States, according to the Centers for Disease Control and Prevention (CDC), but some experts believe BA.2 will eventually become the dominant variant worldwide.

BA.2 is most prevalent in the Health and Human Services (HHS) Region 3, according to data from the CDC, and accounted for about 6.2 percent of last week's cases. Region 3 includes Pennsylvania, West Virginia, Virginia, Delaware and Maryland. Region 2, which is made up of only two states, New York and New Jersey, had 6 percent of its sequenced cases come back as BA.2.

Region 9, which includes the states of California, Nevada, Arizona and Hawaii, had the third-highest percent of BA.2 cases last week, at 5.8 percent. Only two other regions, Region 10 on the West Coast (which includes Alaska, Idaho, Oregon, and Washington and 271 Tribal Nations) and Region 1 on the East Coast (which is made up of all six New England states), had more than five percent of its sequenced cases belong to the BA.2 variant.

Region 7 (Iowa, Kansas Missouri and Nebraska) had the lowest percentage of BA.2 cases last week, according to the CDC, with the subvariant accounting for fewer than 1 percent of cases.

The CDC data only included regional data, it did not break out variant proportions by state.

covid variant stealth united states
The BA.2 COVID variant is most prevalent on the coasts of the United States, although it accounts for fewer than 5 percent of cases nationwide. A Walmart worker shows she tested negative after using one of the new government-issued COVID-19 Antigen Rapid test kits she received to take a self-test while at home on February 8 in Provo, Utah. George Frey/AFP/Getty Images

Nationwide, the BA.2 variant accounted for about 4 percent of all cases in the United States, significantly less than the Omicron variant, according to the CDC. However, its highly transmissible nature means it could become the dominant variant worldwide.

BA.2 has already overtaken the original Omicron variant as the dominant strain in South Africa and Denmark. Dr. Dorit Nitzan, the World Health Organization's (WHO) regional emergency director, told The Jerusalem Post that the "expected trajectory" is that BA.2 will become the dominant variant.

It's unclear what risk the sub-variant poses, although Nitzan said it appears it's even more transmissible than the original Omicron variant. Nitzan suspected Europe will continue to see mutations within the "Omicron tree" but places with lower vaccination rates could have "totally different variants developing right now."

The WHO is monitoring BA.2 but hasn't dubbed it a "variant of concern." It's sometimes dubbed a "stealth variant" because it misses key mutations that distinguish Omicron from other variants in genetic PCR tests, according to Vox. However, Gregory Poland, a professor of medicine and infectious disease at the Mayo Clinic, told the outlet that routine tests can tell if a person is infected with the subvariant.

"I think it's going to be slower and longer to get down to the base level we would have otherwise," Poland told Vox. "This all but guarantees that the people who are unvaccinated, and haven't been infected yet, will be."