Infectious viral diseases are not the dreaded killers and cripplers they were half a century ago, but they still exact a huge toll. Every year in this country influenza kills about 35,000 and requires the hospitalization of nearly a quarter-million. During the last two years, the mosquito-spread West Nile virus has caused more than 11,000 serious illnesses and about 300 deaths. Nearly 4 million Americans have been infected with hepatitis C virus, and there are 25,000 new cases annually. American drug and biotech companies should be burning the midnight oil working on vaccines to prevent such diseases, but flawed public policy has discouraged vaccine development to the point that supplies of lifesaving vaccines are in jeopardy. The fundamental problem is that government policies discourage companies from investing aggressively to develop new vaccines. Producers have abandoned the field in droves, leaving only four major producers and a few dozen products. As a result, the country has experienced dangerous shortages of several essential vaccines, and some school systems have been forced to waive immunization requirements because there aren't enough vaccines available.