I WOULDN’T CALL 11% EXACTLY “RARE.” IT’S NOT “FREQUENT,” BUT IT’S NOT REALLY “RARE,” EITHER. The COVID-19 vaccine rarely causes disease flares in people with rheumatoid arthritis and lupus, according to a study published Wednesday by the journal Arthritis and Rheumatology. “Just 11% of adults with these diseases, which are autoimmune disorders caused by the immune system attacking healthy tissue in error, reported flares in symptoms that required treatment after vaccination, the data showed.”