The impact of COVID-19 vaccination prior to SARS-CoV-2 infection on prevalence of long COVID among a population-based probability sample of Michiganders, 2020-2022

Purpose: To estimate the association between COVID-19 vaccination status at the time of COVID-19 onset and long COVID prevalence. Methods: We used data from the Michigan COVID-19 Recovery Surveillance Study, a population-based probability sample of adults with COVID-19 (n = 4695). We considered 30-day and 90-day long COVID (illness duration ≥30 or ≥90 days, respectively), using Poisson regression to estimate prevalence ratios (PRs) comparing vaccinated (completed an initial series ≥14 days before COVID-19 onset) to unvaccinated individuals (received 0 doses before COVID-19 onset), accounting for differences in age, sex, race and ethnicity, education, employment, health insurance, and rurality/urbanicity. The full unvaccinated comparison group was further divided into historic and concurrent comparison groups based on timing of COVID-19 onset relative to vaccine availability. We used inverse probability of treatment weights to account for sociodemographic differences between groups. Results: Compared to the full unvaccinated comparison group, the adjusted prevalence of 30-day and 90-day long COVID were lower among vaccinated individuals [PR_30-day= 0.57(95%CI:0.49,0.66); PR_90-day= 0.42(95%CI:0.34,0.53)]. Estimates were consistent across comparison groups (full, historic, and concurrent). Conclusions: Long COVID prevalence was 40–60% lower among adults vaccinated (vs. unvaccinated) prior to their COVID-19 onset. COVID-19 vaccination may be an important tool to reduce the burden of long COVID. Keywords: Post-acute COVID-19 syndrome; COVID-19; COVID-19 vaccines; Population-based Abbreviations and acronyms: CDC, Centers for Disease Control and Prevention; CI, Confidence interval; COPD, Chronic obstructive pulmonary disease; COVID-19, Coronavirus disease 2019; CVD, Cardiovascular disease; EHR, Electronic health record; IPTW, Inverse probability of treatment weight; MDSS, Michigan Disease Surveillance System; MI CReSS, Michigan COVID-19 Recovery Surveillance Study; mRNA, Messenger ribonucleic acid; NH, Non-Hispanic; PCR, Polymerase chain reaction; PR, Prevalence ratio; US, United States; WHO, World Health Organization.