Here we go again. Nearly six months after researchers in South Africa identified the Omicron coronavirus variant, two offshoots of the game-changing lineage are once again driving a surge in COVID-19 cases there.
Several studies released in the past week show that the variants — known as BA.4 and BA.5 — are slightly more transmissible than earlier forms of Omicron1, and can dodge some of the immune protection conferred by previous infection and vaccination2,3.
“We’re definitely entering a resurgence in South Africa, and it seems to be driven entirely by BA.4 and BA.5,” says Penny Moore, a virologist at the University of the Witwatersrand in Johannesburg, South Africa, whose team is studying the variants. “We’re seeing crazy numbers of infections. Just within my lab, I have six people off sick.”
However, scientists say it is not yet clear whether BA.4 and BA.5 will cause much of a spike in hospitalizations in South Africa or elsewhere. High levels of population immunity — provided by previous waves of Omicron infection and by vaccination — might blunt much of the damage previously associated with new SARS-CoV-2 variants.
Moreover, the rise of BA.4 and BA.5 — as well as that of another Omicron offshoot in North America — could mean that SARS-CoV-2 waves are beginning to settle into predictable patterns, with new waves periodically emerging from circulating strains (see ‘Omicron’s new identities’). “These are the first signs that the virus is evolving differently” compared with the first two years of the pandemic, when variants seemed to appear out of nowhere, says Tulio de Oliveira, a bioinformatician at Stellenbosch University in South Africa, who led one of the studies.
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