In Sweden, people vaccinated against COVID-19 before a SARS-CoV-2 infection had a lower risk of developing post-COVID-19 condition (PCC; “long COVID”), according to a register-based cohort study. “The findings highlight the importance of primary vaccination against covid-19 to reduce the population burden of PCC,” the authors conclude.
The project included all 589,722 adults with COVID-19 first registered between Dec. 27, 2020, and Feb. 9, 2022, in the 2 largest regions of Sweden. They were followed from first infection until death, emigration, vaccination, reinfection, a PCC diagnosis, or the end of follow-up on Nov. 30, 2022, whichever came first. People who had received 1 or more COVID-19 vaccine doses before infection were considered vaccinated.
Based on a primary outcome of a clinical diagnosis of PCC, the study showed: “Of 299,692 vaccinated individuals with covid-19, 1,201 (0.4%) had a diagnosis of PCC during follow-up, compared with 4,118 (1.4%) of 290,030 unvaccinated individuals. Covid-19 vaccination with any number of doses before infection was associated with a reduced risk of PCC (adjusted hazard ratio 0.42, 95% confidence interval 0.38 to 0.46), with a vaccine effectiveness of 58%. Of the vaccinated individuals, 21,111 received one dose only, 205,650 received two doses, and 72,931 received three or more doses. Vaccine effectiveness against PCC for one dose, two doses, and three or more doses was 21%, 59%, and 73%, respectively.”