Coronavirus disease 2019 vaccination effectiveness based on the 2021 Japanese dialysis registry

The effectiveness of the coronavirus disease (COVID-19) vaccine in Japanese patients undergoing haemodialysis has previously not been evaluated on a large scale. We analyzed data from the Japanese Society for Dialysis Therapy Renal Data Registry (JRDR), covering nearly all Japanese patients undergoing dialysis (~95% coverage), to examine the association between COVID-19 vaccination and infection or mortality.

We used data from the JRDR end-of-year surveys conducted in 2020 and 2021, including information on the COVID-19 vaccination and infection months. COVID-19 infection incidence and its associated mortality rates based on vaccination status (time updated) and odds ratio (OR) (vaccinated vs. unvaccinated) were estimated monthly from April 2021, when vaccination commenced in Japan.

COVID-19 infection analysis included 228 865 patients (215 941 vaccinated and 12 924 unvaccinated patients at the end of 2021). The age- and sex-adjusted ORs (aORs) were significantly lower in August, September, October and November 2021, especially in September (aOR [95% confidence interval (CI)]: 0.25 [0.18-0.36]). Additional adjustments for past medical history and laboratory results rarely affected these results. Similarly, in the COVID-19-related mortality analysis with 228 731 patients, including 216 781 vaccinated and 11 950 unvaccinated at the end of 2021, COVID-19-related mortality risk was significantly lower in the vaccinated group in August, September, October and November (aOR [95% CI]: August, 0.32 [0.12-0.84], September, 0.04 [0.01-0.11]; October, 0.10 [0.01-0.81]; November, 0.05 [0.00-0.79]).

In Japanese patients undergoing haemodialysis, the first or second COVID-19 vaccine dose was significantly associated with decreased COVID-19 infection and mortality rates, suggesting its effectiveness in this population.