Effect of ten-valent pneumococcal conjugate vaccine on invasive pneumococcal disease and nasopharyngeal carriage in Kenya: a longitudinal surveillance study

Abstract

Summary Background Ten-valent pneumococcal conjugate vaccine (PCV10), delivered at 6, 10, and 14 weeks of age was introduced in Kenya in January, 2011, accompanied by a catch-up campaign in Kilifi County for children aged younger than 5 years. Coverage with at least two PCV10 doses in children aged 2–11 months was 80% in 2011 and 84% in 2016; coverage with at least one dose in children aged 12–59 months was 66% in 2011 and 87% in 2016. We aimed to assess PCV10 effect against nasopharyngeal carriage and invasive pneumococcal disease (IPD) in children and adults in Kilifi County. Methods This study was done at the KEMRI-Wellcome Trust Research Programme among residents of the Kilifi Health and Demographic Surveillance System, a rural community on the Kenyan coast covering an area of 891 km 2 . We linked clinical and microbiological surveillance for IPD among admissions of all ages at Kilifi County Hospital, Kenya, which serves the community, to the Kilifi Health and Demographic Surveillance System from 1999 to 2016. We calculated the incidence rate ratio (IRR) comparing the prevaccine (Jan 1, 1999–Dec 31, 2010) and postvaccine (Jan 1, 2012–Dec 31, 2016) eras, adjusted for confounding, and reported percentage reduction in IPD as 1 minus IRR. Annual cross-sectional surveys of nasopharyngeal carriage were done from 2009 to 2016. Findings Surveillance identified 667 cases of IPD in 3 211 403 person-years of observation. Yearly IPD incidence in children younger than 5 years reduced sharply in 2011 following vaccine introduction and remained low (PCV10-type IPD: 60·8 cases per 100 000 in the prevaccine era vs 3·2 per 100 000 in the postvaccine era [adjusted IRR 0·08, 95% CI 0·03–0·22]; IPD caused by any serotype: 81·6 per 100 000 vs 15·3 per 100 000 [0·32, 0·17–0·60]). PCV10-type IPD also declined in the post-vaccination era in unvaccinated age groups (<2 months [no cases in the postvaccine era], 5–14 years [adjusted IRR 0·26, 95% CI 0·11–0·59], and ≥15 years [0·19, 0·07–0·51]). Incidence of non-PCV10-type IPD did not differ between eras. In children younger than 5 years, PCV10-type carriage declined between eras (age-standardised adjusted prevalence ratio 0·26, 95% CI 0·19–0·35) and non-PCV10-type carriage increased (1·71, 1·47–1·99). Interpretation Introduction of PCV10 in Kenya, accompanied by a catch-up campaign, resulted in a substantial reduction in PCV10-type IPD in children and adults without significant replacement disease. Although the catch-up campaign is likely to have brought forward the benefits by several years, the study suggests that routine infant PCV10 immunisation programmes will provide substantial direct and indirect protection in low-income settings in tropical Africa. Funding Gavi, The Vaccine Alliance and The Wellcome Trust of Great Britain.

Impact of 13-valent pneumococcal conjugate vaccine on the incidence of hospitalizations for all-cause pneumonia among children aged less than 5 years in Burkina Faso: An interrupted time-series analysis

“…On October 31, 2013, Burkina Faso introduced the 13-valent pneumococcal conjugate vaccine (PCV13) into its routine immunization programme, based on a three-dose schedule at 6, 10, and 14 weeks of age (World Health Organization, 2013). Many studies have reported significant reductions in the burden of pneumococcal disease following the introduction of pneumococcal conjugate vaccines (PCV), including invasive pneumococcal disease (Hammitt et al, 2019) and pneumonia (Silaba et al, 2019;Mackenzie et al, 2017;Grijalva et al, 2007). Given that the protective effects of PCVs may depend on the country-specific context, post-introduction studies have been set up to assess the impact of PCV13 in Burkina Faso.…”

Determinants of high residual post-PCV13 pneumococcal vaccine type carriage in Blantyre, Malawi: a modelling study

“…in Sub-Saharan African countries, such as Kenya 17,18 , Malawi 19 , The Gambia 20 and South Africa 21 . In November 2011, Malawi introduced the 13-valent pneumococcal conjugate vaccine (PCV13) as part of the national extended program of immunization with a 3+0 schedule (at 6, 10 and 14 weeks of age).…”

Estimating the impact of pneumococcal conjugate vaccines on childhood pneumonia in sub-Saharan Africa: A systematic review

“…This is likely due to the fact that radiological pneumonia is more specific for pneumococcal disease. Overall, there was a consistent decline in pneumococcal pneumonia cases in the post-vaccine period in reported impact studies(27,36,42). Two studies that reported on vaccine effect in HIV infected children showed that pneumococcal vaccine had similar impact as with HIV uninfected children(36,41).…”

“…One study based pneumonia diagnosis on ICD-10 coding from clinical notes(44). Studies reporting on pneumococcal pneumonia were based on culture with occasional confirmation by Polymerase chain reaction (PCR) (42,45,46) except in one study where PCR based method was used as a means of surveillance(42).…”