The first major real-world study of the omicron Covid-19 variant found that it appeared to cause less severe illness in South Africa, where it was first discovered last month, but that two doses of the Pfizer-BioNTech vaccine offer reduced protection against it.

Researchers are racing to determine whether a fast-spreading variant in South Africa poses a threat to COVID vaccines’ effectiveness.

Researchers in South Africa are racing to track the concerning rise of a new variant of the SARS-CoV-2 coronavirus that causes COVID-19. The variant harbours a large number of the mutations found in other variants, including Delta, and it seems to be spreading quickly across South Africa.

A top priority is to follow the variant more closely as it spreads: it was first identified in Botswana earlier this month and has since turned up in a traveller arriving in Hong Kong from South Africa. Scientists are also trying to understand the variant’s properties, such as whether it can evade immune responses triggered by vaccines and whether it causes more or less severe disease than other variants do.

“We’re flying at warp speed,” says Penny Moore, a virologist at the University of the Witwatersrand in Johannesburg, South Africa, whose lab is gauging the variant’s potential to dodge immunity from vaccines and previous infections. There are anecdotal reports of reinfections and of cases in vaccinated individuals, but “at this stage it’s too early to tell anything”, Moore adds.