POLIOMYELITIS - EPIDEMIOLOGY AND PROPHYLAXIS .5. RESULTS OF A 2-DOSE AND 3-DOSE VACCINATION EXPERIMENT

  • 1 January 1977
    • journal article
    • research article
    • Vol. 55  (6) , 755-759
Abstract
In tropical countries, seroconversion rates following oral poliomyelitis vaccination are frequently unsatisfactory. In an area of the Machakos district in Kenya, 4000 children under 5 yr old were registered and are visited fortnightly by trained field staff as part of a comprehensive, population-based, longitudinal surveillance project. It was considered possible that poliomyelitis vaccine, given orally to children 2 or 3 times at home, would produce satisfactory conversion rates. After collection of blood from a random sample of the children, vaccine was given twice to all children under 5 yr old. Blood was then collected a 2nd time from a different sample of children. After a 3rd dose of vaccine, a 3rd blood collection followed. The percentages of the children that received vaccine each round were calculated and the sera tested for antibodies. It appeared that the mean titer was more strongly related to age than to the number of doses of poliomyelitis vaccine received. Improvement of herd immunity after 2 vaccine distributions was significant for a few age groups and for 2 types of vaccine only. In none of the groups was a significant improvement obtained by the 3rd vaccine distribution. The problems associated with vaccination by live poliomyelitis vaccine in tropical countries are discussed in relation to the results.