In a Perspective, David Wendler and colleagues propose guidance on when it can be ethical to continue placebo-controlled COVID-19 vaccine trials after an effective and safe candidate is found - a topic that is particularly relevant given the recent announcements of success in several late-stage clinical trials. Currently, more than 180 COVID-19 vaccines are in development, with at least 12 undergoing phase 3 trials. Given this unprecedented effort, it's likely that one or more candidates will be found safe and efficacious while many others are still being tested. However, discovering a vaccine in a placebo-controlled trial raises several yet-unanswered ethical questions. Should researchers continue that trial as designed? Should trials for other vaccine candidates continue? "With careful planning and systematic assessment of social value and risk, we believe it can be ethical to conduct some placebo-controlled trials of vaccine candidates for COVID-19, even after we have an efficacious vaccine," write Wendler et al. "Doing so may be necessary to effectively address a pandemic that is causing so much harm around the world." According to the authors, some argue that decisions to continue placebo-based trials are unethical as it's in an individual's best interest to receive an effective vaccine rather than participate in clinical studies where they might instead receive a placebo or ineffective candidate. On the other hand, manufacturing and supply challenges suggest that several vaccines may be needed to meet the global need, highlighting the urgency in conducting additional trials. The risks of serious harm that individuals face from COVID-19 vary widely across groups. Wendler et al. argue that by excluding those at high risk from ongoing COVID-19 vaccine trials, the authors suggest that researchers can continue to collect valuable data from participants who are at low risk of experiencing serious harm.
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Journal
Science