Long-term impact of 10-valent pneumococcal conjugate vaccine on invasive pneumococcal disease in Kenya, 2011–2022

Résumé fourni par la source

Background A 10-valent Pneumococcal Conjugate Vaccine (PCV10 Synflorix ) was introduced in Kenya in 2011 but the long-term impact of PCV10 in Africa is unknown. We evaluated PCV10 impact over 12 years in Kilifi, Kenya. Methods Surveillance for Invasive Pneumococcal Disease (IPD) was conducted among residents of the Kilifi Health and Demographic Surveillance System. We estimated the trend of IPD incidence during the post-vaccine period and used age- and serotype-group-specific rate ratios, adjusted for pre-defined confounders (surveillance year for children aged <5 years and proportion investigated among patients with an indication for blood culture), to compare IPD incidence in the post-vs pre-vaccine period. Findings Three-dose coverage of PCV10 among children aged 12–23 months varied from 79.2% to 94.6% annually. There were no significant trends in IPD incidence in the post-vaccine period (all p-values >0.05). Among children aged <5 years, IPD incidence (all serotypes) was 12.7 per 100,000 in the post-vaccine period (2012–2022), significantly lower than in the pre-vaccine period (1999–2010) (adjusted incidence rate ratio [IRR] 0.32; 95% CI 0.18–0.58). It also declined among children aged 5–14 years (aIRR 0.42; 95% CI 0.23–0.77) and persons aged ≥15 years (aIRR 0.62; 95% CI 0.35–1.10). The incidence of vaccine serotype (VT) IPD declined in persons aged <5 years (aIRR 0.09; 95% CI 0.03–0.21), 5–14 years (aIRR 0.20; 95% CI 0.09–0.45) and ≥15 years (aIRR 0.17; 95% CI 0.06–0.45). Among children aged <5 years in the post-vaccine period, 25%, 29%, and 39% of IPD was caused, respectively, by the additional serotypes included in Pneumosil , PCV13/15 and PCV20. Interpretation A wide-ranging catch-up campaign at PCV10 introduction accelerated reductions in VT-IPD incidence which were sustained over the long-term using a three-dose with no booster (3 + 0) infant schedule. There was a considerable residual burden of IPD of which only a minority is covered by currently available higher-valency PCVs, underscoring the need for effective vaccines with greater coverage. Ongoing, high-quality IPD surveillance will be essential to inform future policy deliberations on optimizing the cost-efficiency and impact of the PCV program. Funding Gavi, the Vaccine Alliance (EPIDZO76/M&E73201018) and the Wellcome Trust (203077/Z/16/Z).

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