What We Know About Omicron’s BA.2 Variant So Far

On March 22 the World Health Organization announced that the Omicron subvariant BA.2 had become the dominant form of SARS-CoV-2, the virus that causes COVID, worldwide. BA.2 shares many genetic similarities with its close relative BA.1, which fueled a global resurgence in COVID infections in recent months. But BA.2 is between 30 percent and 50 percent more contagious than BA.1.

Now, as this latest version of SARS-CoV-2 sweeps the planet, pandemic-weary people everywhere are asking the same question: Is society doomed to confront a succession of new viral variants, each one more contagious than the last?

“We still don’t know the full capacity of this virus to evolve and make radically new types of variants,” says Jeffrey Shaman, an infectious disease modeler at Columbia University’s School of Public Health. According to Shaman and other scientists, SARS-CoV-2 still has a lot of genetic leeway left in terms of how it infects human cells and skirts the immune system. New variants can emerge from stepwise changes in the viral sequence. But heavily mutated versions of SARS-CoV-2 that bear little resemblance to their predecessors “have also come from out of the blue,” says Ralph Baric, a virologist at the University of North Carolina at Chapel Hill. “And if any of these variants are better at infecting cells or evading immunity than their predecessors, then you’ll see increased transmission over the strains that came before.”