Pfizer failed to inform pregnant women participating in its clinical trial for the respiratory syncytial virus (RSV) vaccine that the clinical trial of a similar vaccine by GlaxoSmithKline (GSK) was halted after a safety signal revealed a potential risk of preterm births leading to neonatal deaths. Even though Pfizer knew about the potential safety signal and was studying preterm births as an “adverse event of special interest,” it continued to enroll women in its clinical trial and did not fully inform participants of the risks the vaccine may pose to their babies—and in some cases, provided misleading and contradictory statements,...