The US Food and Drug Administration (FDA) awards priority review vouchers (PRVs) as an incentive to encourage development of therapeutics for underserved medical needs. The program, introduced in 2007 for neglected tropical diseases, was expanded to include rare pediatric diseases in 2012 and medical countermeasures in 2016. Of these three programs, the most successful has been for rare pediatric diseases, with studies indicating the pediatric PRV program stimulates clinic...