Omicron Shows Evidence It Can Reinfect Those Who Already Had COVID, Study Says

South African scientists are warning that the Omicron variant could reinfect people who have already battled COVID-19, the Associated Press reported.

A new study has been published on reinfection rates in the country, and the results show an increased rate of reinfections attributed to Omicron compared to other variants.

"This finding has important implications for public health planning, particularly in countries like South Africa with high rates of immunity from prior infection," claimed the study, which has not yet undergone scientific review. "Urgent questions remain regarding whether Omicron is also able to evade vaccine-induced immunity and the potential implications of reduced immunity to infection on protection against severe disease and death."

One of the researchers involved in the study is Anne von Gottberg, a researcher at the University of Witwatersrand who participated in a briefing for the World Health Organization. She elaborated on the findings and stressed the effectiveness of vaccination against COVID-19.

"Previous infection used to protect against Delta, and now with Omicron it doesn't seem to be the case," she said.

Scientists in South Africa and Botswana discovered the variant last week, with its exact origins currently being studied. The variant has been found in multiple countries, including the United States.

For more reporting from the Associated Press, see below.

The researchers did not say what portion of the reinfections were confirmed as Omicron cases—or whether they caused serious illness.

But the timing of the reinfection spike suggests that Omicron "demonstrates substantial population-level evidence for evasion of immunity from prior infection," they wrote.

The study also did not examine the protection offered by vaccination. The vaccines trigger different layers of immune response, some to fend off infection and others to prevent severe disease if someone does become infected.

Much remains unknown about the new variant, including whether it is more contagious, as some health authorities suspect, whether it makes people more seriously ill, and whether it can thwart the vaccine.

But learning how much protection is provided by prior infection is important, especially in parts of the world where much of the population remains to be vaccinated.

The study suggests "omicron will be able to overcome natural and probably vaccine-induced immunity to a significant degree," Paul Hunter, a professor of medicine at the University of East Anglia, said in a written response to the findings. Just how much "is still unclear though it is doubtful that this will represent complete escape."