the decrease in recipient cases and the increase in contact cases in 1965-1972 compared with the previous 3-year period are explained by the general curtailing of routine vaccination of adults after 1964 , a switch from monovalent oral polio vaccine to topv , improved recognition of contact cases and a shift in emphasis from mass vaccination campaigns and communitywide programs to routine vaccination of infants .
C0032375
oral polio vaccine
C0032374
vaccine