To find an effective Zika vaccine, we must include pregnant women in the trials

November 12, 2017

Though the World Health Organization has lifted the emergency alert on the Zika virus, scientists continue their push to develop a vaccine. Late last year, the virus reached Asia, where outbreaks are ongoing. It will remain a global threat to pregnant women as long as humans travel and mosquitoes stow away with them.

The pursuit of a truly effective Zika virus vaccine, however, is handicapped by a long-standing clinical practice: the exclusion of pregnant women from drug development and vaccine trials. The main reason for this is ethical: Why expose a growing fetus, or a mother-to-be, to unknown risks in an experimental setting? Both fetus and mother are classified as “vulnerable” and regarded as members of a protected population. None of the current Phase 1 trials for a Zika vaccine include pregnant women.

As commendable as this practice is, we argue it is more ethical to include pregnant women in certain clinical trials than to exclude them. The tradition of barring mothers-to-be from experimental studies has introduced preventable health risks to pregnant women and, in the case of the Zika virus, their babies.