Can an Omicron coronavirus infection stave off the Delta variant?

A new laboratory study by South African scientists suggests “infection with the SARS-CoV-2 Omicron variant creates a neutralising immune response against the Delta variant.” That is, if a person is infected with the new Omicron coronavirus variant, they may be able to fight off later infections from the Delta variant, the New York Times reports.

The scientists enrolled both previously vaccinated and unvaccinated subjects who were infected with Omicron in South Africa, soon after they started showing symptoms of the coronavirus. They then measured their ability to neutralise both Omicron and Delta variants “at enrollment versus a median of 14 days after enrollment.”

The findings elicited hope: Neutralisation of Omicron increased 14-fold over two weeks, showing “a developing antibody response” to the newly discovered, and highly contagious Omicron variant.

The researchers also emphasise the finding that there was “an enhancement of Delta virus neutralisation”, which increased 4.4-fold.

“The increase in Delta variant neutralisation in individuals infected with Omicron may result in decreased ability of Delta to re-infect those individuals,” said Africa Health Research Institute’s Professor Alex Sigal, who led the study. “If Omicron does prove to be less pathogenic, then this may show that the course of the pandemic has shifted – Omicron will take over, at least for now, and we may have less disruption of our lives.”

“Omicron is likely to push Delta out,” Sigal told the New York Times. “Maybe pushing Delta out is actually a good thing, and we’re looking at something we can live with more easily.”

The study, called “Omicron infection enhances neutralising immunity against Delta”, has not appeared in a scientific journal yet, but it was posted to Africa Health Institute’s website on Monday. It has been submitted as a preprint to medRxiv. Once it is peer reviewed, it will be published in a medical journal.

Independent scientists said while the South African experiment had not been verified yet, the results seemed to make sense. Carl Pearson, an epidemiologist at the London School of Hygiene and Tropical medicine, said the findings were parallel to what was happening at the moment in England.

“Omicron arrives and grows rapidly, and the Delta trend switches to declining,” he said.

Another epidemiologist, Nathan Grubaugh, at the Yale School of Public Health, said he was witnessing the same pattern in Connecticut in the United States.

“We are seeing Omicron exponentially rise while Delta cases are falling,” he said. “This suggests to me that Omicron is outcompeting Delta for susceptible individuals, leaving them less susceptible to Delta in the aftermath, and driving down Delta cases.”

The coronavirus has evolved during the two years it has upended people’s lives and wreaked havoc on daily life, the economy, and social settings. When they first got infected, people used to produce antibodies and immune cells that could protect against reinfection. Thus, it was a rare occasion to be sick again from Covid-19 soon after recovering.

With the advent of new coronavirus variants, such as Alpha and Beta, starting in late 2020, this was no longer the case. Alpha had mutations that helped it spread quickly, like Beta had adaptations that allowed it to get away from antibodies, from a previous Covid-19 infecion or thanks to a vaccine.

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