Effectiveness of seasonal mRNA COVID-19 vaccination against post COVID-19 condition between July 2023 and September 2024 among adults aged ≥ 60 years in Germany: a population-based cohort study

BACKGROUND: Some individuals infected with severe acute respiratory syndrome coronavirus 2 experience long-term symptoms, termed post COVID-19 condition (PCC). Pandemic-era studies have demonstrated moderate effectiveness of COVID-19-vaccines in preventing PCC. However, as population immunity has evolved and variant-adapted vaccines have been introduced, estimates of vaccine effectiveness and disease frequency from the post-pandemic era are needed to guide policy-making and communication. METHODS: We investigated whether one mRNA COVID-19 vaccine dose during the 2023/2024 season was associated with reduced PCC risk in the following six months among adults aged ≥ 60 years in Germany. We conducted a retrospective cohort study using nationwide, outpatient claims data and performed descriptive and Poisson regression analyses. RESULTS: In our cohort of 19,121,674 patients, 3,437,701 (18.0%) received one dose of a seasonal COVID-19 vaccine and 36,830 fulfilled the PCC case definition (incidence: 0.2%). Vaccinated individuals were older (median age 75 years) compared to those who were not vaccinated (71 years), with a higher proportion being female (54% vs. 46% male). 0.08% of vaccinated patients were diagnosed with PCC during study follow-up, compared to 0.22% non-vaccinated. One vaccine dose was associated with lower risk (adjusted Risk Ratio 0.37; 95% CI 0.36-0.39) of receiving a PCC diagnosis at six months post-vaccination compared to no vaccination, translating to a vaccine effectiveness of 63%. CONCLUSION: Our results demonstrate a low PCC-incidence and a strong protective association between seasonal COVID-19 vaccination and PCC during the first post-pandemic season. These findings can help improve acceptance of COVID-19-vaccines and support doctors' and patients' decision-making regarding vaccination.