A model for developing countries of mass serological survey of children vaccinated against diphtheria and tetanus

Abstract

To assess the efficacy of Iran's mass immunization program, 60,000 blood samples were collected from all susceptible age groups and regions of the country. Diphtheria and tetanus antitoxin levels were determined by hemagglutination test. Official reports claim that over 70% of children in Iran receive vaccine during annual mass campaigns. At least 74% of children 3 months-7 years had diphtheria antitoxin titers sufficiently high to prevent infection, while 81-91% of those 7-13 years old were protected. Similarly, 74-82% of children 3 months-7 years had tetanus antitoxin levels high enough to avoid infection, as did 80-90% of older children. Following mass vaccination in Iran, diphtheria morbidity decreased among children but increased among adults. The incidence of tetanus has been significantly decreased in recent years due to an emphasis on immunizing girls and young mothers with adsorbed tetanus toxoid. These findings confirm both the effectiveness of Iran's vaccination campaign and the boosting effect of vaccine in older children. The hemagglutination test can be performed easily in developing countries where laboratory facilities are limited and is recommended for mass serological surveys.