Efficacy of nine-valent pneumococcal conjugate vaccine against pneumonia and invasive pneumococcal disease in The Gambia: randomised, double-blind, placebo-controlled trial.

BACKGROUND: Pneumonia is estimated to cause 2 million deaths every year in children. Streptococcus pneumoniae is the most important cause of severe pneumonia. We aimed to assess the efficacy of a nine-valent pneumococcal conjugate vaccine in children. METHODS: We undertook a randomised, placebo-controlled, double-blind trial in eastern Gambia. Children age 6-51 weeks were randomly allocated three doses of either pneumococcal conjugate vaccine (n=8718) or placebo (8719), with intervals of at least 25 days between doses. Our primary outcome was first episode of radiological pneumonia. Secondary endpoints were clinical or severe clinical pneumonia, invasive pneumococcal disease, and all-cause admissions. Analyses were per protocol and intention to treat. FINDINGS: 529 children assigned vaccine and 568 allocated placebo were not included in the per-protocol analysis. Results of per-protocol and intention-to-treat analyses were similar. By per-protocol analysis, 333 of 8189 children given vaccine had an episode of radiological pneumonia compared with 513 of 8151 who received placebo. Pneumococcal vaccine efficacy was 37% (95% CI 27-45) against first episode of radiological pneumonia. First episodes of clinical pneumonia were reduced overall by 7% (95% CI 1-12). Efficacy of the conjugate vaccine was 77% (51-90) against invasive pneumococcal disease caused by vaccine serotypes, 50% (21-69) against disease caused by all serotypes, and 15% (7-21) against all-cause admissions. We also found an efficacy of 16% (3-28) against mortality. 110 serious adverse events arose in children given the pneumococcal vaccine compared with 131 in those who received placebo. INTERPRETATION: In this rural African setting, pneumococcal conjugate vaccine has high efficacy against radiological pneumonia and invasive pneumococcal disease, and can substantially reduce admissions and improve child survival. Pneumococcal conjugate vaccines should be made available to African infants.

The influence of prematurity and low birthweight on transplacental antibody transfer in a rural West African population.

OBJECTIVE: To determine the influence of prematurity and low birthweight (LBW) on transplacental antibody transfer. METHOD: In a physician-blinded, cross-sectional study of 213 mother--baby pairs in the labour ward of Bansang Hospital, The Gambia, paired maternal and cord serum samples were tested for specific IgG antibody titres for measles virus (MeV), herpes simplex virus type 1 (HSV1), respiratory syncytial virus (RSV), varicella-zoster virus (VZV), tetanus toxoid (TT) and diphtheria toxoid (DT) antigens using enzyme linked immunosorbent assay (ELISA). RESULTS: Prematurity was significantly associated with reduced placental antibody transfer for MeV, HSV1, TT, DT, RSV and VZV. Maternal antibody transfer for MeV, HSV1, TT, DT, RSV and VZV was significantly lower in neonates with LBW than in babies with adequate birthweight (ABW). CONCLUSION: Materno--foetal transfer of antibodies is impaired in prematurity and LBW babies in this Gambian population. Reduction in antibody transfer may further predispose these already vulnerable neonates to bacteria and viral infections. Therefore, alternative vaccination strategies, including earlier vaccination schedules, are needed to provide better protection to these young infants.