In a household, the risk of spreading the omicron variant to another member is three times higher than it is with the delta variant, U.K. health officials estimated [December 10]. And delta, as you may know, is considered highly transmissible.
Why is omicron such a superspreading variant?
The omicron variant multiplies about 70 times faster inside human respiratory tract tissue than the delta variant does, scientists at the University of Hong Kong report. The variant also reaches higher levels in the tissue, compared with delta, 48 hours after infection.
“That’s amazing,” says immunologist Wilfredo Garcia-Beltran, who’s a fellow at the Ragon Institute of Massachusetts General Hospital and wasn’t involved in the study. This finding indicates that mutations in omicron have sped up the process of entering or replicating (or both) inside the tissue.
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Using “fake” or pseudoviruses, they found that omicron’s spike protein — the region that binds to human cells, triggering infection — was much better at helping the virus enter human cells than the spike protein of delta or that of the original coronavirus.
“Strikingly, Omicron was 4-fold more infectious than wild type [the original version of the virus] and 2-fold more infectious than Delta,” Garcia-Beltran and colleagues wrote in their study.
