The World Health Organization is monitoring the Omicron subvariant XBB.1.16, which has been identified in about two dozen countries.
The subvariant has not been found in the United States, but it is similar to the XBB.1.5 subvariant that has been dominant in the country since January.
XBB.1.16 has one additional mutation that, according to lab studies, makes it more infectious and potentially more pathogenic, Maria Van Kerkhove, WHO's technical lead for Covid-19, said at a recent briefing.
"This is one to watch," she said. "It's been in circulation for a few months. We haven't seen a change in severity in individuals or in populations, but that's why we have these systems in place."
Most of the samples of XBB.1.16 are from India, where it has become dominant. Weekly Covid-19 cases in the country have more than doubled in the past week but remain far below peak levels, WHO data shows.
Omicron remains the variant of concern worldwide and hundreds of sublineages continue to circulate.
"We are in a much better situation than we were since the beginning of this pandemic," Van Kerkhove said. "One of the big uncertainties we face going forward is the virus itself. It hasn't settled into a predictable pattern. It continues to evolve."
The number of Covid-19 cases, hospitalizations and deaths continues to fallin the United States. Less than 1% of counties in the United States have a Covid-19 community level of high, according to the US Centers for Disease Control and Prevention.
