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The Pneumoccocal Conjugate Vaccine Impact Study (PCVIS)
The Pneumoccocal Conjugate Vaccine Impact Study (PCVIS) is a large-scale before-after study of the effectiveness of the 10-valent pneumococcal conjugate vaccine (PCV10) in the routine childhood immunisation schedule in Kenya.
The project will compare the incidence rates of invasive pneumococcal disease, radiologically proven pneumonia, and all-cause admissions to hospital in the period before vaccine introduction and the period after vaccine introduction taking account of secular trends in major confounders including HIV, malnutrition, malaria and bed net use. The project is restricted to the residents of the Kilifi Health and Demographic Surveillance System (KHDSS) and the endpoint events will be defined among admissions to Kilifi District Hospital.
PCV10 was introduced into Kilifi District in January 2011. Population-based surveillance for invasive pneumococcal disease was initiated in 2002. The project aims to estimate not just the changing incidence of disease among the population as a whole but the effect of vaccine introduction on children who were not vaccinated - the 'indirect vaccine effect'. In 2009 a system of vaccine monitoring was established to record all immunizations against the KHDSS population register; linkage of the vaccines database to the hospital IPD database will permit an individual-based analysis of the rate of IPD taking account of immunisation status.
As some of the indirect effect of vaccine will be observed amongst adults, the project has also been estimating the incidence of IPD in adults since 2008. A subsidiary aim of study is to calculate the cost effectiveness ratios associated with the new vaccine programme.
The project began in March 2008 and is funded by the Global Alliance for Vaccines and Immunizations (GAVI Alliance) through the PneumoADIP. It is collaboration with the Division of Vaccines and Immunization in the Ministry of Public Health and Sanitation.