Abstract 942 Infectious Diseases Platform, Tuesday, 5/4

Parainfluenza virus type 3 (PIV3) is second to RSV as the most common cause of croup, bronchiolitis and pneumonia in infants. There is no vaccine or antiviral available to prevent or treat PIV3 infection. Bovine PIV3 (BPIV3) has significant homology with human PIV3 and attenuated replication in human respiratory tract epithelium. To evaluate a live attenuated BPIV3 vaccine, 192 infants were randomized to receive 105TCID50 or 106TCID50 BPIV3 vaccine or placebo by intranasal spray at 2, 4, 6 and 12-15 months of age. Other routine childhood vaccines were given concurrently. Safety data were collected for 14 days after each dose on diary cards by parents. Sera were obtained prior to administering doses 1, 3 and 4, and 1 month after doses 3 and 4. Data through dose 3 are presented. Nasal washes for viral shedding were done once between days 5 and 8 following each dose of vaccine. Fever ≥100.6°F occurred significantly more often in the BPIV3 vaccine groups after the 2nd dose, and in the placebo group after the 3rd dose. There were no significant differences between groups in the rates of fever >101°F or in other post-vaccination adverse events. No serious adverse events were attributable to the vaccine. Hemagglutination inhibition (HAI) responses to BPIV3 and proportions shedding BPIV3 are shown in the table below:

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Full size table

After doses 1, 2 and 3, 47%, 34% and 23% of vaccine recipients, respectively, shed BPIV3. In summary, live attenuated BPIV3 vaccine was 1) well-tolerated when given to infants concurrently with other routine vaccines, 2) induced significant rises of HAI antibody to BPIV3 when compared to placebo, and 3) resulted in high rates of nasal shedding of BPIV3 (57%-73%). Both dosages were immunogenic in infants, but the 106 dose resulted in higher rates of BPIV3 shedding than the 105 dose.

Funded by Aviron.