On Mar. 27, 1962, Oral polio vaccine type 3 MOPV was licensed in the U.S., as well as the trivalent product. In 1962, the Vaccine Advisory Committee recommended the restriction of MOPV3 to preschoolers, school-age children, and adults in high-risk groups. Because of the ensuing widespread use of TOPV (with a consequent decrease in the use of MOPV), there are a limited number of reports estimating the risk of VAPP associated with MOPV strains.