Effect of raised type-3 poliovaccine dose on virus excretion

Excretion of attenuated polioviruses after controlled type 3 poliovaccine administration was studied in the district city of Cheb. The usual type 3 dose, 10(5) TCD50, was doubled in some vaccinees. A total of 972 stool samples collected from primary vaccinees and their family members were examined; three samplings were carried out in most of the subjects. At first sampling, 9 weeks after administration of type 1 + 2 mixture and 1 day before administration of type 3, all poliovirus types were isolated from primary vaccinees, but family members were negative. At second sampling, 14 days after type 3 administration, primary vaccinees displayed suppression of type 1 and 2 replication and a not very pronounced increase in type 3 excretion. Family contacts yielded all types, the least frequent being type 1. At sampling three, 5 months after type 3 administration, the not very clear-cut difference (at 2nd sampling) between vaccinees given the two different type 3 doses was completely obliterated; type 1 was not isolated; and type 2 isolations increased above the 2nd-sampling value. The number of type 1 and 3 isolations decreased in family contacts, in contrast to type 2, where an increase occurred. Excretion of types 1 and 2 at the time of type 3 administration did not demonstrably influence the subsequent excretion of type 3. Mothers were contact infected at a slightly higher rate than other family members. Only a part of excretors among family members of vaccinees excreted virus of the same type as the vaccinees (simultaneously or subsequently).