Background: The appearance of very contagious SARS-CoV-2 variants and waning vaccine immunity may indicate the need to return to using universal methods of preventing the spread of COVID-19.
Methods: We performed a multicenter retrospective cohort survey study to describe the methods used in dialysis units to prevent and control the spread of SARS-CoV-2 and also the association between these methods and the incidence of COVID-19 among hemodialyzed (HD) patients before the era of vaccination. The study population included all maintenance HD patients (n = 1569) in 14 dialysis units in the Pomeranian Voivodeship.
Results: The group of 352 patients (199 men, 153 female) were confirmed for COVID-19. The absolute cumulative incidence in the studied period was 22.4%. It varied widely by dialysis units, ranging from 9.4% to 36.9%. Universal preventive methods were applied by all units. Different additional methods were implemented in some stations with varying frequency (36-86%). In order to quantify the scale of the applied additional preventive methods, we calculated a summary prevention index (PI), i.e., one point for one additional method. Lower incidence was found in centers applying dialysis in isolation of patients hospitalized due to diseases requiring hospitalization (17.42% ± 6.89 vs. 26.54 ± 6.34; p = 0.028) and higher incidence in medium-size dialysis centers (ANOVA F: p = 0.017). Significant inverse correlation between PI and incidence was demonstrated as well (r = -0.759; p = 0.002).
Conclusions: The higher the number of implemented preventive measures, the lower the risk of COVID-19 infection in HD patients. Among applied procedures the isolation of hospitalized patients is of significant importance. The measures proved to be effective in prevention before the vaccination era should be continued, as the threat of SARS-CoV-2 still exists.
Keywords: COVID-19; epidemiology; hemodialysis; incidence; prevention.