Abstract
SummaryBackgroundTen-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.MethodsThis 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 km2. 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.FindingsSurveillance 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).InterpretationIntroduction 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.FundingGavi, The Vaccine Alliance and The Wellcome Trust of Great Britain.
Highlights
The number of pneumococcal deaths in children aged 1–59 months was estimated at 317 000 globally in 2015, a decline of more than 50% from 2000.1 In middle-income and high-income countries, inclusion of pneumococcal conjugate vaccines (PCVs) in routine infant vaccination programmes has led to a substantial reduction in the incidence of invasive pneumococcal disease (IPD) caused by vaccine serotypes (VTs)
Evidence before this study In middle-income and high-income countries, inclusion of pneumococcal conjugate vaccines (PCVs) in routine infant vaccination programmes has led to a substantial reduction in the incidence of invasive pneumococcal disease (IPD) caused by vaccine serotypes
There are data from The Gambia showing a reduction in IPD in young children 5 years after the introduction of seven-valent pneumococcal conjugate vaccine and 3 years following the introduction of 13-valent pneumococcal conjugate vaccine, there are no effect data from low-income settings that have adopted ten-valent pneumococcal conjugate vaccine (PCV10)
Summary
The number of pneumococcal deaths in children aged 1–59 months was estimated at 317 000 globally in 2015, a decline of more than 50% from 2000.1 In middle-income and high-income countries, inclusion of pneumococcal conjugate vaccines (PCVs) in routine infant vaccination programmes has led to a substantial reduction in the incidence of invasive pneumococcal disease (IPD) caused by vaccine serotypes (VTs). Evidence before this study In middle-income and high-income countries, inclusion of pneumococcal conjugate vaccines (PCVs) in routine infant vaccination programmes has led to a substantial reduction in the incidence of invasive pneumococcal disease (IPD) caused by vaccine serotypes. This study was planned in 2006, after Gavi, the Vaccine Alliance, made the decision to support introduction of PCVs in lower-income countries It aimed to capture the population effect of PCV introduction in operational use against IPD and nasopharyngeal carriage. Establishing the population effect of PCV in low-resource settings is essential to sustain the commitment of Ministries of Health to PCV programmes
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
