LAUSR

Purpose: The aim of the study was to present the rates of rejection from 2018 to 2021 and evaluate the purported association between COVID-19 vaccination and corneal graft rejection. Methods: Cases of corneal graft rejection diagnosed between January 2018 and December 2021 were reviewed. The conditional Poisson regression model of the self-controlled case series method was used to estimate the incidence risk ratio of graft rejection after COVID-19 vaccination risk period compared with the control period. Based on outcomes of eyes that underwent keratoplasty from January 2018 to December 2020, Cox proportional hazard models were fitted with previous COVID-19 vaccination as a time-varying covariate. Results: Over the past 4 years, the annual tally of diagnosed cases of graft rejection (19 cases in year 2018, 19 cases in year 2019, 21 cases in year 2020, and 18 cases in year 2021) has remained relatively stable. Using the conditional Poisson regression analysis, no significant increase in the incidence rate of rejection in the risk period after COVID-19 vaccination was found (incidence risk ratio = 0.56, 95% confidence interval [CI] = 0.13–2.28, P = 0.70). Fitted as a time-varying covariate, previous COVID-19 vaccination was not associated with graft rejection in both unadjusted (hazard ratio =0.77, 95% CI = 0.29–5.46, P = 0.77) and adjusted Cox models (hazard ratio = 0.75, 95% CI = 0.10–5.52, P = 0.78). Conclusions: No notable increase in rates of corneal graft rejection was noted in year 2021 when COVID-19 vaccination was broadly implemented. The apparent temporal relationship between COVID vaccination and corneal graft rejection may not represent a causative association.