Immunogenicity, safety and reactogenicity of the pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) in 2-17-year-old children with asplenia or splenic dysfunction: A phase 3 study.

BACKGROUND: Immunization with pneumococcal vaccines is an important prophylactic strategy for children with asplenia or splenic dysfunction, who are at high risk of bacterial infections (including S. pneumoniae). This study aimed to assess immunogenicity and safety of pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV, GSK) in this at-risk population.

METHODS: This phase III, multi-centre, open-label, controlled study, in which at-risk children with asplenia or splenic dysfunction were enrolled (age strata: 2-4, 5-10 and 11-17years), was conducted in Poland and the Russian Federation. For the 2-4years at-risk group, healthy age-matched children were enrolled as control. Unprimed children (not previously vaccinated with any pneumococcal vaccine) received 2 PHiD-CV doses (≥2months apart) and pneumococcal vaccine-primed children received 1 dose. Immune responses were assessed pre-vaccination and one month post-each dose. Solicited and unsolicited adverse events (AEs) were recorded for 4 and 31days post-vaccination, respectively, and serious AEs (SAEs) throughout the study.

RESULTS: Of 52 vaccinated children (18 at-risk primed, 28 at-risk unprimed and 6 control unprimed), 45 (18, 23 and 4, respectively) were included in the according-to-protocol cohort for immunogenicity. Post-vaccination (post-dose 1 in primed and post-dose 2 in unprimed children), for each vaccine pneumococcal serotype and vaccine-related serotype 6A all at-risk children had antibody concentrations ≥0.2µg/mL, and for vaccine-related serotype 19A at least 94.4%. Increases in antibody geometric mean concentrations were observed. For most serotypes, all at-risk children had post-vaccination opsonophagocytic activity (OPA) titers ≥8 and increases in OPA geometric mean titers were observed. No safety concerns were raised. One non-fatal SAE (respiratory tract infection, considered not vaccine-related) was reported by one at-risk unprimed child.

CONCLUSION: PHiD-CV was immunogenic and well tolerated in 2-17-year-old children with asplenia or splenic dysfunction. Clinical Trial Registry: www.clinicaltrials.gov, NCT01746108.