What do we know about the new Omicron mutant? It’s a descendant of the earlier super-contagious “stealth Omicron” and has quickly gained ground in the United States. BA.2.12.1 was responsible for 29 per cent of new Covid-19 infections in the United States last week, according to data reported on Tuesday by the US Centres for Disease Control and Prevention. And it caused 58 per cent of reported infections in the New York region. We're now moving to the BA.2.12.1 wave as it has increased to 29% of new cases and will quickly out-compete BA.2 with its heightened infectiousness https://t.co/jjl2AnwOWX today's @CDCgov weekly genomic surveillance update pic.twitter.com/qA1QNJzpZR — Eric Topol (@EricTopol) April 26, 2022 The variant has been detected in at least 13 other countries, but the US has the highest levels of it so far. Scientists say it spreads even faster than stealth Omicron. Cases are rising in places with increasing levels of the BA.2.12.1 variant, such as central New York, suggesting something about it is causing it to out-compete others, said Eli Rosenberg of New York state’s health department. Expect more worrisome Covid-19 variants after Omicron: scientists It appears a similar pattern is likely to play out nationally, said Kirsten St. George, director of virology at New York state’s Wadsworth Centre Laboratory. Scientists are trying to figure out other aspects of BA.2.12.1, including whether vaccines are as effective against it as previous variants.