CHARLOTTE, N.C. — New omicron subvariants BA.4 and BA.5 are gaining ground nationwide.
Tuesday's Centers for Disease Control and Prevention variant update shows the pair collectively make up close to 15% of new COVID-19 cases in the U.S. They comprised 1% of cases a month ago.
BA.4 and BA.5 were first detected in South Africa in January and February and have since gained dominance there.
Last month, European health officials flagged them as variants of concern, due to their higher transmissibility. The European Centre for Disease Prevention and Control said the subvariants can evade immunity from prior infection and from vaccination, particularly if vaccination has waned over time.
The agency said that early studies show immunity properties of BA.4 and BA.5 are "significantly" different than those of BA.1 and BA.2. However, there is no evidence the subvariants cause more severe disease than other omicron strains.
The Carolinas, and the U.S. overall, are seeing a rise in cases and hospitalizations as new omicron subvariants continue to emerge and grow in presence.
Dr. Katie Passaretti, an infectious disease specialist with Atrium Health, said the promising sign, for now, is that coronavirus patients are not increasing as fast as cases are. She attributes that trend to wider-spread immunity from vaccination and boosters, plus prior infection.
"Reinfection is possible, especially if you were infected in kind of the late-December, early-January timeframe, but it kind of acts almost as its own booster that you have some protection against more severe disease," Passaretti said.
BA.2.12.1, another omicron subvariant, became the dominant strain in the U.S. about two weeks ago. Omicron subvariant BA.2 is the dominant strain in North Carolina, according to the state's health department.