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Omicron 3 instances extra prone to trigger reinfection than earlier COVID variants: researchers

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South African scientists say the danger of reinfection from the omicron COVID-19 variant is at the least 3 times increased than for any earlier variant. 

Within the preliminary examine, researchers checked out roughly 2.8 million Positive coronavirus infections between March 2020 and Nov. 27, 2021, and 35,670 suspected reinfections had been recognized.

From this retrospective evaluation, the group mentioned will increase in main an infection had been noticed following the introduction of each the beta and delta variants, however no corresponding improve was noticed within the reinfection hazard.


Moreover, the estimated hazard ratio for reinfection versus main an infection was decrease throughout COVID-19 waves pushed by the beta and delta variants than for the primary wave.

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“In distinction, the latest unfold of the omicron variant has been related to a lower within the hazard of main an infection and a rise in reinfection hazard. The estimated hazard ratio for reinfection versus main an infection for the interval from Nov. 1, 2021, to Nov. 27, 2021, versus wave 1 was 2.39,” the authors wrote

Based mostly on “population-level proof,” they concluded that the omicron mutation is “related to substantial potential to evade immunity from prior an infection.”

“In distinction, there is no such thing as a population-wide epidemiological proof of immune escape related to the beta or delta variants,” the examine learn, and the authors famous that “pressing questions stay concerning whether or not omicron can also be in a position to evade vaccine-induced immunity and the potential implications of diminished immunity to an infection on safety towards extreme illness and loss of life.”

Different variants have been recognized to trigger reinfection, and several other sufferers reinfected with the beta variant were identified in Israel earlier this 12 months.

Juliet Pulliam, a South Africa-based epidemiologist and one of many examine’s authors, tweeted Thursday that the researchers didn’t have details about the vaccination status of people within the knowledge set and “subsequently can’t make any evaluation of whether or not omicron additionally evades vaccine-derived immunity.”

“Immune escape from prior an infection, whether or not or not omicron may evade vaccine-derived immunity, has essential implications for public well being globally, however there’s nonetheless so much we don’t know,” she wrote.


Pulliam mentioned the subsequent steps embody quantifying the extent of the variant of concern’s immune escape for each pure and vaccine-derived immunity, in addition to its transmissibility relative to different variants.

“Knowledge are additionally urgently wanted on illness severity related to omicron an infection, together with in people with a historical past of prior an infection,” she mentioned.

“Earlier an infection used to guard towards delta and now with omicron it doesn’t appear to be the case,” one of many researchers, Anne von Gottberg of the College of Witwatersrand, said at a World Health Organization briefing on Thursday.

“We consider that vaccines will nonetheless, nonetheless, shield towards extreme illness,” she mentioned. 

The crew’s analysis was uploaded to a preprint server and has not but been peer-reviewed. The researchers didn’t say what portion of the reinfections had been confirmed as omicron {cases} — or whether or not they brought on critical sickness.

The most recent variant was found simply over per week in the past by scientists in South Africa and Botswana. A lot stays unknown about the new variant, together with whether or not it’s extra contagious, as some well being authorities suspect, whether or not it makes folks extra severely unwell, and whether or not it might thwart the vaccine.

At a White House COVID-19 response team briefing, Facilities for Illness Management and Prevention (CDC) Director Rochelle Walensky mentioned Friday that omicron {cases} have been detected in round 40 nations.

According to The Washington Post, South Africa’s Nationwide Institute for Communicable Illnesses mentioned Wednesday that omicron overtook different virus variants in November.


New {cases} in South Africa have jumped from about 200 a day final month to greater than 11,500 on Thursday. Within the week since omicron was detected in the country’s most populous province, Gauteng, infections have surged 300%, Well being Minister Joe Phaahla mentioned Friday.

The variant has additionally now unfold to all eight different provinces, he added. Even with the fast improve, infections are nonetheless under the 25,000 every day new {cases} that South Africa reported within the earlier surge, in June and July.

Only 6% of Africa’s inhabitants has been totally vaccinated.

The Related Press contributed to this report.

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