Unnecessary hesitancy on human vaccine tests

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Science  10 Jul 2020:
Vol. 369, Issue 6500, pp. 150-151
DOI: 10.1126/science.abc8264

In their Policy Forum “Ethics of controlled human infection to address COVID-19” (22 May, p. 832), S. K. Shah and colleagues provide an ethical framework to determine whether controlled human infection studies (CHIs) are justifiable for studying potential vaccines and treatments for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (COVID-19). Some of the Policy Forum authors reportedly disagreed that “the social value of such CHIs is sufficient to justify the risks” at this time. Their reluctance is unfounded. The risks of a properly conducted CHI are low enough, and the social value of expedited SARS-CoV-2 vaccine development is high enough, that properly conducted CHIs with a fair chance at accelerating that development remain a legitimate strategy.

Shah et al. identify an ineliminable risk to participants: a 0.03% death rate among “healthy adults aged 20 to 29” infected with SARS-Cov-2. The source for this mortality rate (1) documents death among all infected 20- to 29-year-olds. In healthy people in this age range, death should be rarer. CHIs will only recruit healthy people. And, perhaps thanks to evolving COVID-19 treatment practices, the mortality rate is already lower in that age group than it was when the Policy Forum was published (2). Moreover, as shown in Shah et al.'s table S1, live kidney donation, a broadly accepted practice, carries a similar mortality risk of <0.03%. An alternative suggestion cited by Shah et al. would limit risk to below a 1% death rate (3), but that threshold is far higher than their own estimate of 0.03%.

Further mitigating the overall risk, CHI participation could reduce participants' relative risk—i.e., their risk in the trial minus their risk if they decline to participate (4, 5)—and improve their treatment access (4). Shah et al. agree that recruiting in “locations with high community spread of SARS-CoV-2 could be an acceptable way to reduce relative risks for participants” (6). CHIs should also guarantee participants critical care [which most young COVID-19 patients survive (79)] and any novel therapeutics. Those may be scarce in some locations with high community spread (6), even absent economic or racial injustices that might create ethical complications (5). These factors push overall risk further below limits.

Shah et al. question the social value of CHIs because of the necessary “coordination of stakeholders,” but no trial guarantees coordinated delivery. Even a fairly moderate chance at substantially curbing colossal (10, 11) mortality through an accelerated vaccine rollout would imbue CHIs with high expected social value.

References and Notes

Competing Interests

N.E. is funded by National Institute of Allergy and Infectious Diseases grant R01 AI114617-01A1.

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