Omicron surge may reduce delta infections, South Africa study shows

A small study from South Africa suggests that the spread of the COVID-19 omicron variant may reduce infections from the delta variant, as the former strain builds up immunity against the latter.

The study, which has yet to be peer reviewed, looked at 33 unvaccinated and vaccinated individuals who had contracted the omicron variant, as Reuters reported. It found that people who became infected with the highly transmissible new strain developed an enhanced immunity to the delta variant. This effect was reportedly stronger among those who were vaccinated.

Researchers found that neutralization against delta increased by 4.4-fold over a 14-day period following participants’ enrollment in the study soon after they began experiencing symptoms from omicron infections. A 14-fold increase in neutralization against the omicron variant itself was also observed.

“The increase in Delta variant neutralization in individuals infected with Omicron may result in decreased ability of Delta to re-infect those individuals. Along with emerging data indicating that Omicron, at this time in the pandemic, is less pathogenic than Delta, such an outcome may have positive implications in terms of decreasing the Covid-19 burden of severe disease,” the researchers wrote.

They also said that cross-neutralization does not always occur when people become infected with a different strain, noting that infection from the delta variant did not result in neutralization of the beta strain of the virus.

Omicron has been shown to have a significantly higher degree of mutations than previous strains of the coronavirus, with roughly 30 mutations on its spike proteins.

Despite the study’s findings, researchers also noted that more than half of the participants were vaccinated against COVID-19 and many others were likely previously infected, making it unclear if the antibodies neutralizing the delta variant came from being infected by omicron or from vaccinations or prior infection.