As Congress considers legislation that would allow imitative biological products, known as "biosimilars," to rely on the safety and efficacy data of original innovators, it must ensure that any provisions passed will foster, not stifle, discovery.

Ernst R. Berndt and Anjli C. Warner discuss their new book, U.S. Markets for Vaccines: Characteristics, Case Studies, and Controversies.

The 1984 Hatch-Waxman Act created a streamlined path for generic drugs to reach the market after pioneer drug patents expire. The result has been the most vigorous and competitive generic drug market in the world, but the Hatch-Waxman Act does not apply to most biologics. Isolated from a variety of...