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ba2 As ‘stealth omicron’ (BA2) advances, scientists are learning more The coronavirus mutant widely known as “stealth omicron” is now causing more than a third of new omicron cases around the world, but scientists still don’t know how it could affect the future of the pandemic. Researchers are slowly revealing clues about the strain, a descendant of omicron known as BA.2, while warily watching it become ever more prevalent. Early research suggests it spreads faster than the original omicron and in rare cases can sicken people even if they’ve already had an omicron infection. There’s mixed research on whether it causes more severe disease, but vaccines appear just as effective against it. Overall cases are falling in some places where the variant is becoming more prevalent, offering some hope that the latest troubling version of the virus won’t send cases skyrocketing again as experts try to learn more. BA.2 has lots of mutations. It’s been dubbed “stealth” because it lacks a genetic quirk of the original omicron that allowed health officials to rapidly differentiate it from delta using a certain PCR test. So while the test can detect a BA.2 infection, it looks like a delta infection. Initial research suggests BA.2 is more transmissible than the original omicron — about 30% more contagious by one estimate. But vaccines can protect people from getting sick. Scientists in the United Kingdom found that they provide the same level of protection from both types of omicron. A bout with the original omicron also seems to provide “strong protection” against reinfection with BA.2, according to early studies cited by the WHO. An initial analysis in Denmark showed no differences in hospitalizations for BA.2 compared with the original omicron, which tends to generally cause milder disease than the delta variant. More recently, researchers in South Africa found much the same: a similar risk of hospitalization and severe disease with the original omicron variant and BA.2. COVID-19 cases are dropping globally, including in some of the places where BA.2 is prevalent. “The timing of the upswings and downswings in cases remains unclear,” said Louis Mansky, director of the Institute for Molecular Virology at the University of Minnesota.

us We Might Not Need Annual COVID Shots The vaccines will need an update at some point. But not every variant of concern will warrant one. Last June, as the Delta variant sat poised to take the globe by storm, Pfizer’s CEO, Albert Bourla, promised the world speed. Should an ultra-mutated version of SARS-CoV-2 sprout, he said, his company could have a variant-specific shot ready for rollout in about 100 days—a pledge he echoed in November when Omicron reared its head. Now, with the 100-day finish line fast approaching and no clinical-trial data in sight, the company seems unlikely to meet its mark. (I asked Pfizer about this super-speedster timeline; “when we have the data analyzed, we will share an update,” the company responded.) Moderna, which started brewing up an Omicron vaccine around the same time, is eyeing late summer for its own debut. Not that an Omicron vaccine would necessarily make a huge difference, even if Pfizer had made good. In many parts of the world, the variant’s record-breaking wave is receding. Having a bespoke vaccine in 100 days would have been an unprecedented accomplishment, but Omicron was simply “too fast” for a cooked-to-order shot to beat it, says Soumya Swaminathan, the chief scientist at the World Health Organization.