Evidence on the associations and safety of COVID-19 vaccination and post COVID-19 condition: An updated living systematic review

Abstract

Post COVID-19 condition (PCC) refers to persistent symptoms occurring ≥12 weeks after COVID-19. This living systematic review (SR) assessed the impact of vaccination on PCC and vaccine safety among those with PCC, and was previously published with data up to December 2022. Searches were updated to 31 January 2024 and standard SR methodology was followed. Seventy-eight observational studies were included (47 new). There is moderate confidence that two doses pre-infection reduces the odds of PCC (pooled OR (pOR) 0.69, 95% CI 0.64-0.74, I2 = 35.16%). There is low confidence for remaining outcomes of one dose and three or more doses. A booster dose may further reduce the odds of PCC compared to only a primary series (pOR 0.85, 95% CI 0.74-0.98, I2 = 16.85%). Among children ≤18 years old, vaccination may not reduce the odds (pOR 0.79, 95% CI 0.56-1.11, I2 = 37.2%) of PCC. One study suggests that vaccination within 12 weeks post-infection may reduce the odds of PCC. For those with PCC, vaccination appears safe (four studies) and may reduce the odds of PCC persistence (pOR 0.73, 95% CI 0.57-0.92, I2 = 15.5%).