Factors predicting fatality among healthcare workers infected with Ebola in the Democratic Republic of Congo, August 2018 – June 2020

Introduction: Ebolavirus disease (EVD) threatens global public health with fatality rates of 25% – 90%. From August 2018 to June 2020, the Democratic Republic of Congo (DRC) reported several EVD infections, including deaths among healthcare workers (HCWs). We analysed the factors predicting death among infected HCWs during the 10th Ebola outbreak in the DRC. Methods: We conducted a retrospective cohort study using data from healthcare providers and frontline responders infected with Ebolavirus in North Kivu and Ituri provinces from August 2018 to June 2020. The outcome variable was the time in days from admission to death; the exposure variables were high viral load (Ct value ≤ 20), previous Ebolavirus vaccination, duration from onset to admission (DOA), socio-demographic and clinical factors. We calculated the hazard rate of dying among the subjects; we ensured that the global proportional assumption was met and ran all the exposure variables in a Cox proportional hazard regression at 5% significance level using STATA-17 to assess how they predicted the hazard of dying among the subjects, and we finally performed a backward elimination of factors to select the best-fitting model. Results: We analyzed data from 145 admitted HCWs out of 172 total infections recorded. Among them, the hazard rate of dying was 3 deaths per 100 infected-HCWs per day; 40 (27.59%) of them had Ct ≤ 20 and 52 (35.86%) died. Factors increasing hazard of dying were Ct ≤ 20 (aHR= 3.43, 95%CI: 1.78 – 6.59), DOA ≥ 5 days (aHR =2.23, 95%CI: 1.19 – 4.19), non-previous Ebola vaccination (aHR =2.56, 95%CI: 1.21 – 4.42), confusion (aHR 3.70, 95%CI: 1.05 – 13.05), vomiting (aHR= 2.76, 95%CI: 1.31 – 5.81) and sore throat (aHR =2.94, 95%CI: 1.05 – 8.23). Conclusions: High viral load, delayed admission, non-previous Ebola vaccination, confusion, vomiting, and sore throat were associated with increased hazard for death among infected HCWs. Strengthening early diagnosis, timely admission for appropriate treatment, and mandatory Ebola vaccination of HCWs should be advocated to reduce fatality among HCWs during future EVD outbreaks.