Antibodies against poliomyelitis and measles viruses in immunized and unimmunized children, Ghana 1976-78.

The serological response of children to two doses of live oral poliomyelitis vaccine (the first at age 3-8 months and the second at age 9-14 months) and to one dose of measles vaccine (at age 9-14 months) was determined in two regions of Ghana. The seroconversion rates after two doses of poliomyelitis vaccine were lower than expected-24% for poliovirus type 1, 60% for type 2, and 52% for type 3; 23% of the subjects were triple negative. A third dose of the vaccine increased the seroconversion rates to 36%, 73%, and 61% for poliovirus types 1, 2, and 3, respectively; the rate for triple negatives fell to 8%. In the course of the study it was found that there was an intensive circulation of wild polioviruses and that a high proportion of 3-8 month-old infants had maternal antibodies.The seroconversion rate following one dose of measles vaccine was about 90%, a response similar to that obtained in temperate climates. The two main conclusions drawn from the study were: (1) two doses of poliomyelitis vaccine are inadequate to provide protection against poliomyelitis in developing countries; and (2) in developing countries measles vaccine should be given as soon as possible after the age of 8 months.