South African scientists warn that reinfection among people who have already battled COVID-19 appears more likely with the new omicron variant than with previous mutations of the coronavirus.

A research group that followed re-infection in South Africa reported an increase with the arrival of the omicron variant that was not recorded in the country with the previous two variants, even with the more contagious delta variant.

The results, published online Thursday, are preliminary and have not yet been the subject of scientific review. The researchers also did not specify how many re-infections were confirmed as omicron cases or whether they caused severe disease.

However, the peak infection again, by the time it occurs, reveals strong evidence that immunity to previous infections is waning, the scientists said.

“Previous infections were used to protect against the delta variant and now with Omicron this does not appear to be the case,” one of the researchers, Anne von Guttberg of the University of the Witwatersrand, said in a WHO briefing. Thursday.

The study also did not analyze the protection provided by the vaccine. Vaccines trigger different levels of immune responses, some to prevent infection and others to prevent severe illness should a person become infected.

“However, we believe that vaccines can still protect against severe disease,” von Guttberg said.

Scientists discovered the latest variant just over a week ago in South Africa and Botswana, and it has now been found in several countries. Much remains unknown about the new variant, even if it is more contagious, as some authorities suspect, if it causes more serious illness or if it could evade the vaccine.

But it is important to know how much protection a previous infection provides, especially in parts of the world where much of the population is still not immune.

In a written response to the study, Paul Hunter, MD, professor of medicine at the University of East Anglia, said the study indicates that “the omicron variant would be able to significantly overcome natural and possibly vaccine-induced immunity.” Rn what the action is “is not yet clear, although it is doubtful that this represents the full scope.”