COVID-19 may increase the risk of autoimmune inflammatory rheumatic diseases (AIRDs) for up to 1 year after infection, according to a two-country study published today in the Annals of Internal Medicine.

The study, led by researchers from the Broad Institute at MIT and Harvard and from Kyung Hee University in Seoul, South Korea, analyzed national claims databases from more than 10 million Korean and 12 million Japanese patients aged 20 years and older diagnosed as having COVID-19 from January 2020 to December 2021.

The study period was dominated by the wild-type virus and then the Delta variant. The COVID-19 patients were compared with matched flu patients from the same period and uninfected controls.