Measles in Jordan: a prototype of the problems with measles in developing countries

Until recently measles was a very severe illness of infancy and early childhood in Jordan. Incidence rates were estimated to be as high as 500 to 1000/100,000 and case fatality rates were as high as 10%. Since 1981 mandatory and routine vaccination was introduced by the Ministry of Health. Because infants accounted for the most severe cases and almost all mortality, measles vaccine was given at 9 months of age. No booster doses were recommended. Since 1981 there has been a steady shift in the age distribution of cases toward the older age group. In recent years children > 5 years of age accounted for > 60% of cases. Commensurate with that the mortality rate has decreased to almost nil in recent years. There is also evidence of a marked decrease of inpatient admission of measles cases to one of the largest hospitals, the Jordan University Hospital. Despite high immunization rates in excess of 88%, however, outbreaks of measles continue to occur. To evaluate the impact of measles vaccination on outbreaks, a study in one village in 1987 showed that there was almost no protective efficacy in children > 5 years of age (relative risk 0.80 and confidence interval 0.06 to 0.67 vs. relative risk 0.73 and confidence interval 0.54 to 1.15). Although the current measles immunization strategy has decreased the mortality and morbidity rates, we propose that the continuing occurrence of outbreaks necessitates the addition of a booster dose after 15 months of age.(ABSTRACT TRUNCATED AT 250 WORDS)