Cold passage 18 (CP18) parainfluenza virus type 3 (PIV-3) vaccine was evaluated in a double-blind, randomized, placebo-controlled study of 95 infants and young children. None of 19 seropositive older children 41 to 124 months old became infected when 106 50% tissue culture infective doses (TCID50) of vaccine virus was administered intranasally. Two of nine and seven of twenty-four young seropositive children given 105 or 106 TCID50 of CP18 PIV-3, respectively, became infected. Each of four seronegative young children became infected, as indicated by virus shedding and antibody response, when given 106 TCID50 of CP18 PIV-3 intranasally. Illness was not observed in seropositive children. Two of the four seronegative children developed a mild illness characterized by rhinorrhea and wheezing on auscultation; none had fever. In one case, vaccine virus spread from a vaccinee to a sibling control but did not cause illness. The vaccine is attenuated relative to wild-type PIV-3, but additional attenuation will be required to achieve a satisfactory PIV-3 vaccine.
ASJC Scopus subject areas
- Microbiology (medical)