Several new and highly immune-evasive strains of SARSCoV2 have caught scientists’ attention in recent weeks; one or more may well cause big, new COVID19 waves this fall and winter.
Nearly 3 years into the pandemic, SARS-CoV-2 faces a formidable challenge: finding new ways around the immunity humans have built up through vaccines and countless infections. Worrisome new data show it is up to the challenge. Several new and highly immune-evasive strains of the virus have caught scientists’ attention in recent weeks; one or more may well cause big, new COVID-19 waves this fall and winter.
The strains that look poised to drive the latest comeback are all subvariants of Omicron, which swept the globe over the past year. Several derived from BA.2, a strain that succeeded the initial BA.1 strain of Omicron but then was itself outcompeted in most places by BA.5, which has dominated in recent months. One of these, BA.2.75.2, seems to be spreading quickly in India, Singapore, and parts of Europe. Other new immune-evading strains have evolved from BA.5, including BQ.1.
Both groups also found that BA.2.75.2 seems very good at evading immunity in humans. In a preprint posted on 19 September, immunologist Ben Murrell at the Karolinska Institute and his colleagues reported that serum samples from 18 blood donors in Stockholm—where vaccination rates are high and prior infections widespread—. “This is the most resistant variant we’ve ever evaluated,” says Karolinska virologist Daniel Sheward.