Pneumococcal Conjugate Vaccine Impact Study (PCVIS)

PCVIS is a large-scale before-after study of the effectiveness of PCV-10 in Kenya. PCV10 was introduced into Kilifi District in January 2011. The project is restricted to the residents of the Kilifi Health and Demographic Surveillance System (KHDSS) and the endpoint events are defined among admissions to Kilifi District Hospital (KDH) and from cross sectional surveys of the KDHSS population.
Total impact refers to the effectiveness of PCV-10 delivered under operational conditions via the Kenya childhood immunization programme. Vaccine effectiveness in this case refers to the direct effect i.e. the benefits of vaccination to vaccinated children and the indirect effect, which are benefits to the unvaccinated children and adults.

PCVIS has established a system of longitudinal IPD surveillance to detect pneumococcal disease caused by vaccine and non-vaccine containing pneumococcal serotypes of pneumococcus (figure 1 is an example of the output from this surveillance system). Using this system, the total impact of PCV-10 use will be determined by measuring the total change in IPD incidence and hospital burden following programmatic introduction of PCV-10

IPD Summaries

Vaccine Monitoring System (VMS)
The PCVIS study (and its sub-studies) is embedded in the Vaccine Monitoring System (VMS). Starting November 2008, the VMS has continually captured all childhood vaccination information including all doses given in 34 health facilities (map below) providing childhood immunization services.  We also monitor episodes of adult disease and paediatric disease with surveillance of all adults and children admitted to Kilifi County Hospital, and we monitor naso-pharyngeal carriage using swabs collected from 500 randomly selected individuals of all ages and cultured for S. pneumoniae and H. influenzae and S. aureus. 

Vaccine Safety Study (VAEIK)
Vaccine Adverse Events In Kenya (VAIEK) is a population-based, post-introduction vaccine safety surveillance study of PCV10 in Kenya that has helped to inform World Health Organization (WHO) vaccine policy. Synflorix (PCV10) is a 10-valent vaccine against pneumonia presented as a 2-dose vial without a preservative. The vaccine was introduced in the routine immunisation schedule in Kenya in February 2011. This is the first time a preservative-free multi-dose vaccine is being used in a developing country.
This is a separate but related project. Safety surveillance was conducted at four sites (the Kilifi HDSS, the KEMRI CDC Research and Public Health Collaboration International Emerging Infections Program population-based disease surveillance sites in Kibera and Rarieda Districts and the KEMRI/CDC HDSS site in Siaya District). In Kilifi, surveillance took place at all health facilities where the PCVIS project is capturing vaccination data. The VAIEK study has provided data on the use of preservative-free vaccines in developing countries such as Kenya. In August 2013, an end of study report was submitted to WHO, the study did not provide evidence that introduction of PCV10 in Kenya has increased the risk of abscess, shock or death following immunisation.



Investigators : Investigators: Anthony Scott, Laura Hammitt, Susan Morpeth, Shahnaaz Shariff, Tatu Kamau, Anthony Etyang, Kenneth Munge, Micah Silabah, Tahreni Bwanaali, Ifedayo Adetifa