Work

The impact of introduction of the 10-valent pneumococcal conjugate vaccine on pneumococcal carriage in Nigeria

Year: 2023

Type: article

Abstract: Background Pneumococcal Conjugate Vaccines (PCVs) reduce the burden of pneumococcal disease by reducing nasopharyngeal acquisition and transmission of serotypes in the vaccines (vaccine-serotypes). Following introduction of the 10-valent PCV (PCV10) in Nigeria, we assessed the population-level impact of PCV introduction on pneumococcal carriage. Methods We conducted annual cross-sectional carriage and vaccination coverage surveys between 2016 and 2020 in rural and urban sites in Nigeria. We recruited a random sample of residents and used WHO-recommended laboratory methods to identify pneumococcal serotypes. We modelled prevalence ratios for the change in annual carriage prevalence using log-binomial regression, and explored the association between vaccination coverage in children <5 years and changes in the population-level vaccine-serotype carriage. Findings We enrolled 4,684 and 3,653 participants for the carriage surveys and 2,135 and 1,106 children for the coverage surveys in the rural and urban sites, respectively. Carriage prevalence of vaccine-serotypes declined steadily with increasing levels of PCV10 coverage among children aged <5 years. From 2016 to 2020, coverage with three doses of PCV10 increased from 7% to 59% and from 15% to 81% in the rural and urban sites, respectively. Prevalence ratios for the annual change in vaccine-serotype carriage in participants aged <5 years and ≥5 years were 0.84 (95% CI:0.79-0.89) and 0.86 (95%CI:0.80-0.89) in the rural, and 0.69 (95% CI:0.62-0.77), and 0.83 (95% CI:0.74-0.93) in the urban sites. Conclusions We found significant reduction in vaccine-serotype carriage at a population level following a steady increase in PCV10 coverage, indicating direct and indirect vaccine effects.

Source: Nature Communications

DOI: 10.1038/s41467-023-38277-z