The research is among the earliest evidence that immunization substantially decreases the risk of long Covid even when a breakthrough infection occurs. Already, researchers had said that by preventing many infections entirely, vaccines would reduce the number of cases of long Covid, but it wasn’t clear what the risk would be for people who still got infected after vaccination.

“We found that the odds of having symptoms for 28 days or more after post-vaccination infection were approximately halved by having two vaccine doses,” researchers wrote in the study, published in the journal The Lancet Infectious Diseases. “This result suggests that the risk of long Covid is reduced in individuals who have received double vaccination, when additionally considering the already documented reduced risk of infection overall.”…

The new research had limitations, the authors acknowledged. It was based on people self-reporting their test results and vaccination status. The sample of people who participated also included more women than men and disproportionately few people from “more deprived areas” of the country. It also did not determine any differences by race and ethnicity.