The Study

Census Data Collection, Kilifi County, Kenya

The Pneumococcal Conjugate Vaccine Impact Study (PCVIS) is a large-scale before-after study of the impact of 10-valent pneumococcal conjugate vaccine (PCV10) in Kenya.

The pneumococcal immunization campaign in Kenya

PCV10 was introduced into the routine infant vaccination programme in Kenya in January 2011, accompanied by a catch-up campaign in Kilifi County for children under five.


The project gathers vaccine coverage data, and compares the incidence rates of invasive pneumococcal disease, clinically-defined and radiologically proven pneumonia, and all-cause admissions to Kilifi County Hospital before and after vaccine introduction.


The study measures the direct impact of PCV10 among vaccinated individuals and any indirect protection on the unvaccinated population afforded by the vaccine. Early on, PCVIS established the safety of PCV10 in a field setting, and more recently, PCVIS has been tracking serotype replacement disease.

Cost effectiveness

PCVIS also models the cost effectiveness of PCV10, and future research will investigate how the vaccine could be administered effectively at a lower unit cost. This is an important consideration because PCV10 is the most expensive vaccine in the childhood immunization programme in Kenya, and subsidy will start to be reduced from 2021.