The trial tests the recombinant vesicular stomatitis virus Ebola vaccine (rVSV-ZEBOV), which was developed by the Public Health Agency of Canada, and licensed to NewLink Genetics and Merck. rVSV-ZEBOV was selected based on its safety profile, induction of potentially protective immune responses, including neutralising antibodies, and availability of vaccine doses.
In a ring vaccination trial, the control arm could be a placebo or a vaccine against a disease not under study. This was deemed unacceptable in Guinea because of national and international concerns about leaving vulnerable individuals unprotected against EVD when a potentially effective vaccine was available. An assessment of the epidemiology of EVD in Guinea was done, which suggested that a 21 day delay, the incubation period in which 95% of EVD cases arise for the control arm could be sufficient to determine efficacy, while meeting the requirement to minimise study participants’ time without vaccination. In Guinea the trial is open label, but in settings with fewer operational challenges a ring vaccination trial of immediate versus delayed vaccination could include blinding of allocation by using additional visits to each study arm for the administration and follow-up of a placebo or non-study vaccine. In the Ebola ça suffit ring vaccination trial, both the immediate and delayed vaccination arms receive equivalent infection prevention and control advice at enrolment. This includes informing study participants that the vaccine may not offer protection, so they should not take risks with Ebola exposure, and that the vaccine may not prevent Ebola in people already infected.
QUIZ
The placebo control arm is not enabled in the case of Ebola because
A. In 95% of cases incubation period is estimated as 21 days.
B. Delayed vaccination is already suggested
C. International concerns about unprotected individual.
A
ReplyDeleteanswer C
DeleteC
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