Impact of 10-valent pneumococcal conjugate vaccine on invasive pneumococcal disease and nasopharyngeal carriage in Kenya

Hammitt, L.; Etyang, A. O.; Morpeth, S. C.; Ojal, J.; Mutuku, A.; Mturi, N.; Moisi, J.; Adetifa, I.; Karani, A.; Akech, D.; Otiende, M.; Bwanaali, T.; Wafula, J.; Mataza, C.; Mumbo, E.; Tabu, C.; Deloria Knoll, M.; Bauni, E.; Marsh, K.; Williams, T.; Kamau, T.; Sharif, S.; Levine, O.; Scott, J. A. G.

doi:10.1101/369876

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bioRxiv · 10.1101/369876

Impact of 10-valent pneumococcal conjugate vaccine on invasive pneumococcal disease and nasopharyngeal carriage in Kenya

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Abstract

Background10-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 <5 years. Coverage with [≥]2 PCV10 doses in children 2-11 months was 80% in 2011 and 84% in 2016; coverage with [≥]1 dose in children 12-59 months was 66% and 87%, respectively.\n\nMethodsClinical and microbiological surveillance for invasive pneumococcal disease (IPD) among admissions of all ages at Kilifi County Hospital was linked to the Kilifi Health and Demographic Surveillance System from 1999-2016. We calculated the incidence rate ratio (IRR) comparing the pre-vaccine and post-vaccine eras, adjusted for confounding, and reported percent reduction in IPD as 1-IRR. Annual cross-sectional surveys of nasopharyngeal carriage were conducted from 2009-2016.\n\nFindingsSurveillance identified 667 IPD cases in 3,211,403 person-years of observation. IPD incidence in children <5 years fell sharply in 2011 following PCV10 introduction, and remained low (PCV10-type IPD: 60{middle dot}8 vs 3{middle dot}2/100,000 [92% reduction; 95%CI: 78, 97]; overall IPD: 81{middle dot}6 vs 15{middle dot}3/100,000 [68% reduction; 95%CI: 40, 83]; 1999-2010 vs 2012-2016). PCV10-type IPD also declined significantly in unvaccinated age groups (<2 months, 5-14 years, [≥]15 years), with estimated reductions of 100%, 74%, and 81%, respectively. There was no significant change in the incidence of non-PCV10 type IPD. In children aged <5 years, PCV10-type carriage declined by 74% and non-PCV10-type carriage increased by 71%.\n\nInterpretationIntroduction of PCV10 in Kenya resulted in a substantial reduction in PCV10-type IPD in children and adults without significant replacement disease. These findings suggest that routine infant PCV10 immunization programmes with catch-up campaigns will provide substantial direct and indirect protection in low-income settings in tropical Africa.

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Hammitt, L., Etyang, A. O., Morpeth, S. C., Ojal, J., Mutuku, A., Mturi, N., Moisi, J., Adetifa, I., Karani, A., Akech, D., Otiende, M., Bwanaali, T., Wafula, J., Mataza, C., Mumbo, E., Tabu, C., Deloria Knoll, M., Bauni, E., Marsh, K., Williams, T., Kamau, T., Sharif, S., Levine, O., Scott, J. A. G.. 2018-07-18. Impact of 10-valent pneumococcal conjugate vaccine on invasive pneumococcal disease and nasopharyngeal carriage in Kenya. https://doi.org/10.1101/369876

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