Omicron's ability to evade immunity from prior infection. The paper was uploaded on a medical preprint server and has not yet been peer-reviewed.
There were 35,670 suspected reinfections among 2.8 million individuals with positive tests until November 27. Cases were considered reinfections if they tested positive 90 days apart. "Recent reinfections have occurred in individuals whose primary infections occurred across all three waves, with the most having their primary infection in the Delta wave," tweeted Juliet Pulliam, director of the South African DSI-NRF Centre of Excellence in Epidemiological Modelling and Analysis.