Reinfection from Omicron three times higher than for any previous variant

The risk of reinfection from the Omicron coronavirus variant is three times higher than for any previous variant, according to a South African study of infections since the start of the pandemic.

The finding provides evidence of omicron’s “ability to evade immunity from prior infection,” according to the authors, Juliet Pulliam of the South African Center for Epidemiological Modelling and Analysis and Harry Moultrie of the National Center for Communicable Diseases.

The study was based on data collected through South Africa’s health system on about 2.8 million confirmed coronavirus infections between March 2020 and Nov. 27, the authors wrote in an emailed statement. Of those, 35,670 were suspected reinfections.

“Our most urgent priority now is to quantify the extent of omicron’s immune escape for both natural and vaccine-derived immunity, as well as its transmissibility relative to other variants and impact on disease severity,” they wrote.

South Africa announced the discovery of a new variant, later named omicron, on 25 November as cases began to spike and the strain spread across the globe. National daily cases almost doubled on Wednesday, days after countries across the world halted flights to and from southern Africa.

Scientists working with the provincial government of Gauteng, the South African province that’s the epicenter of the outbreak of the omicron coronavirus variant, aim to complete a study into its virulence by Tuesday.

The province, South Africa’s most populous, has been in focus since the government and scientists it’s working with said on Nov. 25 that the new variant had been identified in samples from the area. That roiled global markers and saw travel bans imposed on southern Africa.

“Is this variant less virulent? We don’t have the answers to that yet,” said Bruce Mellado, the chairman of the Gauteng Premier’s Advisory Committee, in an interview Thursday. “Our advisory committee is doing it as we speak. We will most likely have a presentation to the command council, behind closed doors, on Tuesday.”

The results of the study would later be released to the public, said Mellado, who is a professor at Johannesburg’s University of The Witwatersrand, who uses mathematical modeling to predict the trajectory of infections.

Lower Deaths

So far hospitalizations and mortality are lower than expected, he said.

In the week ended 21 Novemberthe number of excess deaths, a measure of deaths measured against an historical average, in Gauteng were 62 below normal, according to a report from the South African Medical Research Council.

Excess deaths are seen as a more accurate measure of the true impact of Covid-19 than official deaths. Since the pandemic began South Africa’s official deaths from the disease stand at about 90,000, a third of the excess death total.

“We are very surprised,” he said, adding that earlier infections and vaccinations may have given some protection as cases surge. “Even if this strain is less virulent it will still bring death and suffering to lots of people.”


Read: South Africa can’t survive travel bans: health minister

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Reinfection from Omicron three times higher than for any previous variant