An emerging variant of COVID-19 called BA.2.86 that caused alarm in the summer of 2023 has landed on the Center for Disease Control and Prevention’s radar again.
The variant accounted for nearly 9% of cases during the 2-week period ending Nov. 25, up from 3% during the previous 2 weeks, according to data published Nov. 27 by the CDC. The estimates are not exact, and the CDC indicated the actual percentage of cases may range from 5% to 15%.
The CDC took the unusual step of publishing a specific statement about the rise in BA.2.86 cases. The variant drew worldwide attention during the summer because of how different its makeup is, compared with other prominent variants of the virus that causes COVID-19, raising the potential for the new variant to be more capable of causing infection. But after a flurry of interest in BA.2.86, it didn’t end up being as widespread as expected, so for months it wasn’t listed as a standalone variant on the CDC’s variant tracker list.
“At this time, BA.2.86 does not appear to be driving increases in infections or hospitalizations in the United States,” the CDC wrote in its advisory. “It is not possible at this time to know whether BA.2.86 infection produces different symptoms from other variants. In general, symptoms of COVID-19 tend to be similar across variants. The types of symptoms and how severe they are usually depend more on a person’s immunity than which variant causes the infection.”
BA.2.86 is now the third-most prominent variant circulating the United States, behind HV.1 and EG.5, which combined account for about 45% of all U.S. COVID-19 cases. All three are from the Omicron lineage of the virus.
About 8% of all COVID tests reported to the CDC were positive for the week ending Nov. 18, which is a decline, compared with recent weeks. But indicators for severe cases of the illness have ticked up lately, including rises among ED visits for COVID, hospitalizations, and deaths.
A version of this article appeared on WebMD.com.