On Apr. 26, 1955, Officials first noticed an increase in reported polio cases in California. Soon it was learned that 200,000 had been inoculated with a vaccine produced by Cutter Laboratories that contained live virus.

The ﾓCutter Incidentﾔ resulted in 200 children developing permanent paralysis and 10 deaths. Inoculations continued with vaccine produced by the five other companies, and by the end of 1955, 10 million children in five countries had been inoculated.