ESTIMATION OF THE RISK OF ASEPTIC-MENINGITIS ASSOCIATED WITH MUMPS VACCINATION, FRANCE, 1991-1993

Background. Several published studies have recently shown a higher inc idence of aseptic meningitis associated with Urabe AM-9 vaccine strain than that estimated previously. In France, where all mumps vaccines p roduced and marketed contain the Urabe AM-9 vaccine strain, little was known about the incidence of these side effects although several surv eillance systems exist. Methods. The capture-recapture method can be u sed to estimate the total number of cases of a disease when at least t wo independent data sources are available. Applying the capture-recapt ure method, data provided by the national network of hospital virology laboratories (EPIVIR) and by the Pharmacovigilance Department of the vaccine manufacturer (P.M.sv.) during a 3-year period between 1 Januar y 1991 and 31 December 1993 have been used to obtain an estimate of th e total number of aseptic meningitis cases associated with Urabe AM-9 vaccine. Results. The number of such aseptic meningitis cases was esti mated at 116 (95% confidence interval [CI] : 49-183). The risk of asep tic meningitis can thus be assessed as 1 case per 28 400 doses of Urab e AM-9 sold (95% confidence interval [CI] : 1 case per 18 000-1 case p er 67 200). The sensitivity of the systems was 21% for EPIVIR and 23% for P.M.sv. The low number of cases recorded by either system makes it difficult to test the statistical independence of the two systems by the calculation of the correlation coefficient of the sensitivity of t he systems after stratification. However, the stratified data by age, by sex, by geographical zone and by type of vaccine show that the tota ls after stratification are not very different from the crude total. C onclusions. The French Vaccination Committee has recommended promoting the practice of measles-mumps-rubella vaccination in order to limit t he circulation of the wild virus and to prevent an epidemic in insuffi ciently protected groups of the population, whilst awaiting vaccine co ntaining the Jeryl-Lynn strain.