Researchers tracked 6,729 volunteers ages 18 to 69, who got two shots of either AstraZeneca’s viral vector vaccine or an mRNA vaccine from Pfizer/BioNTech or Moderna after recovering from an infection with the coronavirus and who reported long COVID symptoms of any severity at least once between February and September 2021.
The odds of reporting long COVID – symptoms lasting at least 12 weeks – fell by an average of 13% after a first vaccine dose, the researchers reported on Wednesday in The BMJ. The second dose, given 12 weeks after the first, was associated with a further 9% decrease in the odds of long COVID that persisted for at least 9 weeks, on average, the researchers said. The odds of reporting long COVID severe enough to result in functional impairment were similarly reduced, researchers reported.
Outcomes were similar regardless of vaccine type, interval from infection to first vaccine dose, underlying health status, or severity of COVID-19. However, the study was not designed to detect such differences, nor can it definitively prove that vaccines lower the odds of long COVID.
“Further research is required to evaluate the long-term relationship between vaccination and long COVID, in particular the impact of the Omicron variant,” which emerged after this study ended, the researchers said.