While omicron has been shown to be highly transmissible and can evade some antibodies, after two weeks of getting symptoms immunity to subsequent infections from the strain rose 14-fold, according to the authors led by Alex Sigal and Khadija Khan of the Durban, South Africa-based Africa Health Research Institute. A smaller improvement was found against delta, they said.

“If we are lucky, omicron is less pathogenic, and this immunity will help push delta out,” said Sigal, who has previously found a two-dose course of Pfizer Inc. and BioNTech SE’s Covid-19 shot as well as a previous infection may give stronger protection against omicron.

The study is based on 15 participants, of which two were excluded as they didn’t detectably neutralize omicron, and the data are being submitted to MedRxiv, a preprint medical publication. It has not been peer reviewed.

Since the participants had probably suffered previous Covid-19 infections and were largely vaccinated, it’s not clear if the results show the impact on delta by omicron-elicited antibodies or the activation of antibodies, the authors said.