Vaccination and the risk of post-acute sequelae after COVID-19 in the Omicron-predominant period

Objectives To assess the association of primary and third doses of vaccination with the risk of post-acute sequelae of COVID-19. Methods This retrospective cohort study utilized a combined database of nationwide health care claims data, COVID-19 patient registry, and vaccination records from South Korea. Individuals diagnosed with COVID-19 in the Omicron variant-dominant period of January–March 2022 were tracked for 30–120 days post-infection. The exposure of interest was the receipt of primary and third doses of the SARS-CoV-2 vaccine. The occurrence of 26 specific conditions in eight domains was compared using Cox regression with inverse probability of treatment weighting. Results This study included 394 773 unvaccinated individuals and 7 604 081 individuals receiving ≥2 doses of vaccine. Compared with unvaccinated individuals, vaccination with at least two doses was associated with a reduced risk (adjusted hazard ratio; 95% CI) of several conditions, including ischaemic heart disease (0.73; 0.57–0.94), heart failure (0.55; 0.48–0.63), cardiac dysrhythmia (0.72; 0.61–0.85), cardiac arrest (0.41; 0.33–0.51), pulmonary embolism (0.66; 0.52–0.84), venous thromboembolism (0.54; 0.44–0.66), acute renal failure (0.56; 0.46–0.67), new dialysis (0.45; 0.34–0.59), chronic obstructive pulmonary disease (0.74; 0.65–0.84), acute pancreatitis (0.64; 0.51–0.80), and diabetes (0.82; 0.71–0.95). The risks of heart failure, cardiac dysrhythmias, cardiac arrest, pulmonary embolism, and new dialysis were lower in those who were vaccinated with three doses compared with those who were vaccinated with two doses. Discussion Vaccination was associated with a decreased risk of post-acute sequelae of COVID-19, suggesting its potential role in mitigating the indirect impacts of COVID-19.