Purified fusion protein vaccine protects against lower respiratory tract illness during respiratory syncytial virus season in children with cystic fibrosis.

OBJECTIVE

To test in a double blind, placebo-controlled study a purified fusion protein (PFP-2) vaccine against respiratory syncytial virus (RSV) in RSV-seropositive children with cystic fibrosis (CF).

METHODS

Seventeen CF children, mean age 4.5 years, received PFP-2 vaccine and 17 CF children, mean age 5.8 years, received a saline vaccine. At enrollment the Shwachman clinical score, Brasfield radiographic score, oxygen saturation (SpO2), anthropometric indices and other variables were recorded. After vaccination the reactions were assessed daily for 7 days. During the RSV season weekly telephone interviews were performed and children with an acute respiratory illness were evaluated and cultured for RSV. Serum was drawn before vaccination, 1 month after vaccination and at the end of the RSV season and tested for antibodies to RSV.

RESULTS

Other than age the baseline measurements at enrollment were similar between groups. The PFP-2 vaccine produced mild local reactions and induced a significant neutralizing antibody response in two-thirds of the vaccinees and a significant enzyme-linked immunosorbent assay-fusion glycoprotein antibody response in nearly all the PFP-2 vaccinees. Vaccine-enhanced disease was not observed in PFP-2 vaccines infected with RSV. Protection against RSV infection was not observed; however, a significant reduction (t test, P < 0.01) in mean number of lower respiratory tract illnesses (0.8 vs. 2.1), antibiotic courses (2.2 vs 4.5) and days ill (30.5 vs. 67) occurred among RSV-infected PFP-2 vaccinees.

CONCLUSIONS

Efficacy of the PFP-2 vaccine against lower respiratory tract illness during the RSV season was shown in RSV-seropositive children with CF.