Feasibility and safety of rVSV-ZEBOV vaccination of humanitarian health workers against Ebola virus disease: an observational study.

BACKGROUND AND RATIONALE: Geneva University Hospitals were granted a temporary authorization to administer the recombinant live vesicular stomatitis virus rVSV-ZEBOV (Ervebo®) vaccine to expatriate humanitarian frontline workers (FLWs) prior to mission deployment.

OBJECTIVES

Our aims were to assess the feasibility of FLW vaccination before deployment and to report adverse events (AEs).

METHODS

FLWs received a single injection of rVSV-ZEBOV (>7.2E7 plaque forming unit) during their pre-deployment medical check-up at the Travel Medicine Clinic of the Geneva University Hospitals (Day 0). A safety questionnaire regarding potential AEs was emailed to FLWs on Days 3 and 21. Early and delayed AEs were those starting within 3 or 21 days of vaccination, respectively.

RESULTS

Between 1 August 2019 and 30 June 2020, 124 FLWs received the rVSV-ZEBOV vaccine. Eighty-six volunteers (86/124; 69%) received a concomitant vaccine. The response rate to the follow-up questionnaire was 88 and 55% at Days 3 and 21, respectively. Most respondents (105/109; 96.3%), experienced at least one AE, with a mean of three (±SD 1.75) AEs per person. The most common AE was injection site pain, followed by fever (53/109; 48.6%), fatigue (51/109; 46.7%) and myalgia (49/109; 44.9%). Most early AEs (360/377; 95.4%) resolved within 3 days, reflecting vaccine reactogenicity. Delayed AEs were reported by 6/69 (7.2%) subjects, the median time to symptom onset was 11 days (range: 5-14); half of them were joint-related AEs (3/6). Four serious adverse events (SAE) were observed: two cases of high grade fever, one rash and one case of arthritis. Two suspected unexpected serious adverse reactions were observed: one case of continuing recurrent transient dizziness and fatigue considered related to the vaccine; and one case of presbyopia that was deemed unrelated.

CONCLUSION

AEs to rVSV-ZEBOV were common but in general transient and were well tolerated, pre-deployment rVSV-ZEBOV vaccination in FLW is feasible and can be included with pre-mission check-up.