South Africa study suggests Omicron infection could boost immunity against Delta variant

Preliminary findings from a study suggest that infection with the Omicron variant of coronavirus could boost a person's immunity against the more severe Delta variant.

South African scientists at the Africa Health Research Institute in Durban examined 33 unvaccinated and vaccinated individuals who had contracted the Omicron variant, Reuters reported. They found that people who were infected with Omicron developed enhanced immunity to the Delta variant. Their immunity was even stronger if they had previously been vaccinated against COVID-19.

The study, which has not yet been peer-reviewed, also finds that Omicron could displace Delta as the dominant coronavirus variant.

"The increase in Delta variant neutralization in individuals infected with Omicron may result in decreased ability of Delta to re-infect those individuals," the study's authors said.

Researchers found that neutralization of Omicron increased 14-fold over 14 days after participants were enrolled in the study. They also found there was a 4.4-fold increase in neutralization of the Delta variant.

The study's authors explained the results are "consistent with Omicron displacing the Delta variant, since it can elicit immunity which neutralizes Delta making re-infection with Delta less likely."

Scientists are optimistic that if Omicron proves to cause less severe disease than Delta, the pandemic may finally end. The ultimate question is whether Omicron is less pathogenic compared to Delta. "If so, then the incidence of COVID-19 severe disease would be reduced and the infection may shift to become less disruptive to individuals and society," the authors wrote.

There is reason for hope. The wave of Omicron cases experienced in South Africa quickly subsided within weeks after it was first reported, even though only 48.3% of the population is fully vaccinated, according to Our World in Data.

Alex Sigal, a professor at the Africa Health Research Institute in South Africa, explained on Twitter Monday that if Omicron behaves as observed in South Africa, it will "help push Delta out" and possibly lead to the end of COVID-19 disrupting our lives.

Previous studies from South Africa have indicated there is reduced risk of hospitalization and severe disease in people infected with the Omicron variant compared with Delta, though the authors caution that some of this is likely due to high population immunity, Reuters reported.

COVID-19 hospitalizations in the U.S. have risen in recent weeks as Omicron variant cases have surged, causing new daily average case records in several states.

As of Monday morning, more than 71,000 COVID-19 patients were hospitalized across the U.S., according to the Department of Health and Human Services. At the height of the Delta variant surge this year, more than 100,000 people were hospitalized with COVID-19, according to UPI.