Omicron more infectious than Delta; evades immunity from prior infection: Study

The Omicron variant is likely to cause three times more reinfections as compared to the Delta variant that wreaked havoc earlier this year. On top of that, the variant is believed to have substantial ability to evade immunity from prior infections, showed a study by South African scientists.

These findings come as India reported its first Omicron cases on Thursday. Two individuals in Karnataka were detected with the variant. While the government has urged the people to not panic, emergency meetings are being scheduled and fresh standard operating procedures (SOPs) are likely.


The Omicron variant is believed to be more infectious than other strains such as the Delta or Beta, the study showed. The study, however, is yet to be peer reviewed.

Juliet Pulliam, director of the South African DSI-NRF Centre of Excellence in Epidemiological Modelling and Analysis said that recent infections occurred in individuals who have had “primary infections occurred across all three waves, with the most having their primary infection in the Delta wave”.

“We find evidence of increased reinfection risk associated with emergence of the Omicron variant, suggesting evasion of immunity from prior infection,” she added.

Pulliam stated that the authors did not have the information on the vaccination status of the individuals. So while they stated that the variant can successfully evade immunity from prior infection, they are yet to ascertain if Omicron evades vaccine-induced immunity.

“Immune escape from prior infection, whether or not Omicron can also evade vaccine derived immunity, has important implications for public health globally, but there is still a lot we don’t know,” Pulliam stated.


Two individuals — a 46-year-old doctor from Bengaluru and a 66-year-old South African national — have been detected with the Omicron COVID-19 variant. The Karnataka government is undertaking contact tracing.

According to reports, five contacts of one of the patients have reported positive for COVID-19. These patients have been isolated and their samples are being tested for Omicron.

Also read: Omicron variant: India reports first two cases; what we know so far

Leave a Reply

Your email address will not be published. Required fields are marked *