Johannesburg: The Omicron variant is three times more likely to cause reinfections compared to the Delta or Beta strains, a preliminary study by South African scientists published on Thursday suggested.
The findings are based on data collected by South Africa’s health system. The outcome of the study is the first epidemiological evidence about Omicron’s ability to evade immunity from prior infection, reported news agency AFP.
The scientists’ paper was uploaded on a medical preprint server but is yet to peer-reviewed.
Among 2.8 million individuals with positive reports till November 27, there were 35,670 suspected reinfections. Cases were considered reinfections if they tested positive 90 days apart.
“Recent reinfections have occurred in individuals whose primary infections occurred across all three waves, with the most having their primary infection in the Delta wave,” director of the South African DSI-NRF Centre of Excellence in Epidemiological Modelling and Analysis, Juliet Pulliam tweeted.
Pulliam sounded a note of caution that the authors had no information about the individuals’ vaccination status and so could not assess to what extent Omicron evades vaccine-induced immunity. The researchers are planning to study this next.
“Data are also urgently needed on disease severity associated with Omicron infection, including in individuals with a history of prior infection,” she said.
A scientist at the University of Southampton, Michael Head, praised the research as “high quality.”
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