#4363 MULTINATIONAL COMPARATIVE EFFICACY OF 6 DIFFERENT COVID-19 VACCINES FOR THE PREVENTION OF BREAKTHROUGH INFECTION AND MORTALITY IN HD PATIENTS
Authors: Haarhaus Mathias , Woitas Rainer Peter , Veiga Pedro Mota , Santos Carla , Alhomrani Mohammed , Silva Eliana , Lucas Carlos , Macário Fernando 
Published: June 2023

Abstract

Background and Aims
COVID-19 vaccines induce specific immune responses to reduce COVID-19 infections and severe complications. Dialysis patients exhibit increased COVID-19-related incidence rates and mortality due to poor immune responses. We studied retrospectively the efficacy of 6 different COVID-19 vaccines as well as the combination of vaccines for the prevention of new COVID-19 infections and related mortality in a large multi-national hemodialysis cohort.

Method
All patients from 22 countries in Europe, Asia, Africa, and South America, 18 years or older, registered within in the network of a multi-national dialysis provider on January 31st 2021, were included into the study. We analyzed the incidence of symptomatic COVID-19 in HD patients with vaccination status after 2 doses of 6 different SARS-CoV-2 vaccines in comparison to HD patients who did not receive any vaccine. Patients were screened for COVID-19 symptoms at each dialysis visit and SARS-CoV-2 PCR tests were performed in all symptomatic patients. All PCR-confirmed COVID-19 infections, and deaths occurring between January 31st, and July 15th, 2021 were analyzed. Results were stratified by vaccine type and compared to unvaccinated patients. Data are presented as incidence rate ratios per 1000 patient days and odds ratios vs. no vaccine (95% CI).

Results
Of 38342 eligible patients registered on the index date, 2413 were excluded due to a positive SARS-CoV-2 PCR within 3 months before baseline and 26 were excluded due to unclear vaccination data. The remaining 35903 patients were analyzed. 7816 patients (21.7%) had received a single vaccine dose and 18853 patients (52.5%) had received two doses of any COVID-19 vaccine (Vaxzevria 3180 and 1321, Comirnaty 2823 and 13116, Spikevax 185 and 1521, Sputnik V 1194 and 432, Sinovac 266 and 1722, Sinopharm 168 and 416, or any combination of two different vaccines 325). The 9119 patients (25.4%) who remained unvaccinated during the observational period showed an incidence rate of 0.74/1000 patient days. In the cohort of patients vaccinated two times, 232 developed Covid-19. The lowest incidence rate ratio was observed in patients that had received Spikevax 0.06 (0.02-0.14). By contrast, patients after Sinopharm, Sinovac, and Sputnik V exhibited highest incidence rate ratios 0.53 (0.21-1.09), 0.46 (0.34-0.61), 0.68 (0.34-1.23), respectively. The largest sub-cohort of 13116 patients, who had received Comirnaty, however, had an incidence rate ratio of 0.15 (0.12-0.17). Albeit incidence rates and ratios were heterogenous, all vaccines including Sputnik V showed a significant efficacy to reduce mortality compared to no vaccine.

Conclusion
Combinations of different vaccines and two doses of mRNA-based vaccines very effectively prevented breakthrough infections. Despite considerable differences in preventing COVID-19 infections, all vaccines effectively reduced mortality, compared to no vaccines, in this high-risk dialysis patient cohort.