Measles vaccination status, delay in recognizing measles outbreaks and outbreak outcome

From July to October 1994, Mashonaland East Province in Zimbabwe experienced measles outbreaks in which 2118 cases were reported. According to routine statistics, 69 pc of these patients were previously vaccinated against measles, 22 pc were not vaccinated and 9 pc had an unknown vaccination status. The measles vaccine coverages in the nine districts of this province during the year prior to the outbreak ranged from 58 pc to 87 pc with a provincial average of 72 pc. Three hundred and fifty eight patients who came in contact with health services during one month were investigated further. The prevalence of measles related complications among vaccinated and unvaccinated patients was 18,5 pc and 51,7 pc respectively (X2 = 56,01, p < 0,001; df = 2. While no death occurred among vaccinated patients, the case fatality rate among unvaccinated patients was 27,3 pc (X2 = 45,15, p < 0,001; df = 2). The later an outbreak was recognized the longer it was likely to last and the higher the case fatality rate was (Correlation coefficient = 0,76; 95 pc CI 0,02 - 0,96). It is concluded that the Expanded Programme on Immunization in this area is not a failure and that for outbreak control measures to be effective, they have to be implemented as early as possible, preferably within one week of the onset of an outbreak. District managers should put more emphasis on the use of data by Rural Health Centre staff in order to recognize outbreaks early.