An offshoot of the Omicron variant could be harder to distinguish from other variants through routine PCR tests, scientists have warned, making it more difficult to track the global spread of the heavily mutated strain.
Omicron, first detected in southern Africa, can be identified by a certain type of PCR test because it does not possess one of the three coronavirus gene targets — the S gene — analysed by widely used commercial detection kits.
The World Health Organization has said this characteristic can be used as a marker to detect the variant without the need for full genome sequencing.
But an offshoot of Omicron, identified in at least seven cases across South Africa, Australia and Canada, no longer possesses this genetic quirk. This could make it more difficult to track the spread of Omicron globally, according to experts, especially for countries with limited access to genome sequencing.
Importantly, PCR tests would still be able to detect infection, and viral evolution has been seen both with other variants and other viruses altogether.
Prof Sarah Otto, a theoretical biologist at the University of British Columbia, said the S-gene dropout had been “hugely important” in tracking the early rise of Omicron in South Africa, and added that it “verified that Omicron can spread faster than Delta”.
The Omicron sibling possesses a series of other mutations, which could mean it spreads differently. But Dave Stuart, a professor of structural biology at Oxford university, said there was no reason for immediate concern.
“I don’t think there’s any reason to think that the new outlier is any more of a threat than the form of Omicron that’s knocking around at the moment in the UK, but it is terribly early,” he said. “If countries have access to good genome sequencing, then we’ll have a pretty good handle on it.”
Scientists and global health officials have warned that uneven access to genomic sequencing, either because of a lack of knowhow,…