Antibody response to pneumococcal conjugate vaccine 10 among Nigerian children under 5 years

Introduction: Invasive pneumococcal diseases have been a major contributor to childhood mortality, particularly in the devel-oping world and pneumococcal vaccines were introduced to reduce the burden. The Pneumococcal Conjugate Vaccine 10 (PCV 10) was incorporated into the Nigerian National Programme on Immunization (NPI) in 2014 to reduce the incidence of child-hood pneumococcal infections. This study was done to determine the immunogenicity of the vaccine in our clime.Methodology: This cross-sectional study was carried out between September 2019 and January 2020 at the Children Outpatient Clinic of the Federal Medical Center, Owerri, Nigeria. Two hundred and forty five children between the ages of 20 weeks and 59 months, who had received three doses of Pneumococcal Conjugate Vaccine 10 (PCV 10) at 6, 10 and 14 weeks according to the NPI schedule, were recruited into the study. The anti-pneumococcal PCV 10 IgG concentration was determined using Human Anti-Pneumococcal CPS 10 IgG vaccine ELISA Kit & REG;. Simple proportions, means and median (as appropriate) were used to analyse the data. Kruskal Wallis test and Spearman's correlation were done to test association. Significance was set as p< 0.05.Results: The mean anti-pneumococcal IgG concentration was 11.01 & PLUSMN;1.23 IU/ml and all the study participants formed pro-tective levels of anti-pneumococcal IgG. There was a slight positive correlation between antibody response and age (r=0.13, p=0.04), and the antibody response was slightly more in males than females. Conclusion: All the children under the age of five years who had received PCV 10 at 6, 10 and 14 weeks of age, who partici- pated in this study formed protective levels of antibodies to the vaccine. Antibody levels increased slightly with age. The PCV 10 currently used in the Nigerian programme is sufficiently antigenic and a downward trend in pneumococcal diseases should soon be noticeable.