| Abstract: | The excretion of live, attenuated poliovirus vaccine strains was determined in the feces of Prague Infants home children given 10(5) PFU of type 1 and 2 and 2.10(5) PFU of type 3 vaccine in a routine annual mass campaign. The first two faeces specimens examined in each vaccinee prior to immunization were negative for the virus. A total of 476 stool specimens were collected from 37 children at weekly intervals for a period of 18 weeks. The presence of type 1 poliovirus in the faeces of children given monovalent type 1 vaccine was detectable for 9 weeks, with a maximum in first week, and the virus was isolated in 74.2% of vaccinees. The timing of bivalent type 2 and type 3 vaccine was 9 weeks after monovalent type 1 immunization. The excretion of these two types of poliovirus was found to persist for at least 6 weeks. Type 2 poliovirus was isolated in all vaccinees, type 3 in 70.4% of children. The highest percentage of children excreting type 2 poliovirus was recorded in the first week, the excretion of type 3 peaked three weeks after bivaccine administration. The excretion peaks were reached relatively early postvaccination, with type poliovirus reaching the highest titre per 1 g of faeces. After revaccination (one year later) with monovalent type 1 vaccine, the vaccine strain of type 1 poliovirus could be detected for 6 weeks and was present in the highest percentage of positive stool samples.(ABSTRACT TRUNCATED AT 250 WORDS) |
