Epidemiologic background for the need of rotavirus vaccine in Finland. Preliminary experience of RIT 4237 strain of live attenuated rotavirus vaccine in adults.
Epidemiologic evidence from Finland indicates a dramatic change in the seasonal pattern of acute diarrhoea over the past 30 years. While in the 1950's the majority of cases occurred in late summer the seasonal peak in the 1970's was in winter and spring, coinciding with the prevalence of rotavirus infections. It is not possible to determine retrospectively the aetiologic agents involved in the summer diarrhoea, but EPEC may have been one of them, as EPEC are quite rare in Finland today compared to the 1950's. Another change over the time period is a shift in the age distribution of acute diarrhoea from neonates towards older infants. Rotavirus is today associated with approximately 50% of the cases of acute diarrhoea in children in Finland. Based on experience in one Central Hospital it was estimated that the treatment of rotavirus infections may require some 7300 hospital days in Finland annually, which figure is comparable to that of mumps. As a recent cost-benefit analysis in Finland indicated that a mumps vaccination programme would be economically quite efficacious, the same could be assumed to be true for rotavirus vaccination, provided that an effective and safe vaccine was available. In a preliminary trial of RIT 4237 strain of live attenuated rotavirus vaccine in 20 healthy adult volunteers no clinical symptoms and no excretion of vaccine virus were observed. Rotavirus ELISA antibody booster response was found in 1/20 vaccinees.