Young and middle-aged adults who were infected with earlier versions of the Omicron variant of SARS-CoV-2 are likely to have strong protection against reinfection with the current dominant strains, new research suggests.

Prior infection with pre-Omicron variants also offered some protection against BA.4/BA.5 reinfection, but the Qatari authors said this was “modest” in comparison.

In a pre-print study published on medRxiv ahead of peer review, the Weill Cornell Medicine-Qatar-led team in Doha used data from some 38,000 adults to determine the level of immunity against SARS-CoV-2 reinfection.

After accounting for vaccination status, they found that a prior Omicron infection was found to be 76-80% effective against symptomatic and asymptomatic BA.4/BA.5 reinfection.