Impact of COVID-19 vaccines in patients on hemodialysis: an Italian multicentre cohort study

Background: The aim of this study was to evaluate the impact on the national health system of COVID-19 infection in vaccinated patients undergoing haemodialysis. Methods: From the cohort of vaccinated dialysis patients enrolled in 118 dialysis centres, we calculated hospitalisation incidence in COVID-19-infected subjects. COVID-19-related hospitalisations and ICU admissions were analysed over two time periods (prior to administration of the third dose and following administration of the third dose of vaccine) and adjusted for several co-variates. Using the general population as the reference, we then calculated the Standardized Incidence Ratio (SIR) of hospitalisation. Results: Eighty-two subjects out of 1096 infected patients were hospitalised (7.5%) and sixty-four hospitalisations occurred among the 824 infected persons after the third dose. Age ≥ 60 years (Adj RR 2.91; 95% CI 1.34–6.30) and lung disease (Adj RR = 2.45; 95% CI 1.32–4.54) were the only risk factors associated with hospitalisation. The risk of ICU admission in the second time period (Time 2) was reduced by 86% (RR = 0.14; 95% CI 0.03–0.71) compared to the first time period (Time 1). The SIR of hospitalisation (SIR 14.51; 95% CI 11.37–17.65) and ICU admission (SIR 14.58; 95% CI 2.91–26.24) showed an increase in the number of events in dialysis patients compared to the general population. Conclusions: Our analysis revealed that while the second variant of the virus increased infection rates, it was concurrently associated with mitigated severity of infections. Dialysis patients exhibited a higher susceptibility to both COVID-19 hospitalisation and ICU admission than the general population throughout the pandemic. Graphical abstract: (Figure presented.)