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[Evaluation of changes in the epidemiological situation of SSPE in Poland in the years 1977-1991 (in the course of 15 years after the introduction of mandatory antimeasles vaccination)].

The authors present the results of an epidemiological study of SSPE in Poland conducted since 15 years. Since the years covered by the study (1977-1991) included the first period after the introduction of obligatory vaccinations against measles in our country, the most important aim of this analysis was to find out the possible influence of the effect of these vaccinations on SSPE incidence. A comparison of the data obtained in successive stages of the study shows that a slow gradual decrease of the annual incidence of SSPE has been taking place in our country (from at least 1.6 per million before 1983 to 0.69 in 1991). The effect of the vaccinations is visible also in a significant increase of the mean age of SSPE onset which is a result of ever more widespread vaccination of the youngest children. These observations indicate unequivocally that the aetiological factor in SSPE is a wild strain of measles virus and not that used for vaccinations.