Coronavirus Disease 2019 Vaccination Booster Effectiveness Based on the 2022 Japanese Dialysis Registry.

Aim: To evaluate the effectiveness of the third, fourth, and fifth booster doses (rolled out in December 2021, June 2022, and October 2022, respectively) of the coronavirus disease 2019 (COVID-19) vaccine in Japanese haemodialysis patients during the Omicron era.

Methods: We analysed the Japanese Society for Dialysis Therapy Renal Data Registry (JRDR) year-end survey data from 2021 to 2022, which included information on the number of vaccinations and the most recent vaccination and infection months. For each month of 2022, the COVID-19 infection and related mortality risks were calculated by vaccination status, followed by logistic regression analyses to estimate adjusted odds ratios (aORs).

Results: Overall, 225 887 patients were analysed, including 13 440 (5.9%), 25 547 (11.3%), 64 242 (28.4%), and 122 658 (54.3%) with ≤ 2, 3, 4, and 5 doses at the end of 2022, respectively. The third dose was significantly correlated with a lower risk of COVID-19 infection in early 2022 (March: aOR 0.53 [0.43-0.64]; April: 0.77 [0.63-0.95]) but was associated with a higher risk during mid-2022, coinciding with the BA.1/2 to BA.5 transition (July: 1.65 [1.39-1.95]; August: 2.37 [2.06-2.71]). The third dose consistently correlated with reduced COVID-19-related mortality. The fourth and fifth doses correlated with lower infection risk and COVID-19-related mortality throughout the period.

Conclusion: Among Japanese haemodialysis patients, the third to fifth COVID-19 vaccine doses were associated with reduced infection risk (except in July and August for third doses) and mortality.