The Pneumococcal Conjugate Vaccine Impact Study (PCVIS)

PI

Anthony Scott

team

TEAM

Mike EnglishJames Jay BerkleyAnthony EtyangSusan MorpethTom WilliamsEvasius Bauni

Others — Tahareni Bwanaali,  Lena Matata,  Laura Hammitt,  Patricia Njuguna,   Edna Ogada, Nobert Peshu, Angela Karani, Salim Mwarumba, P Ayieko, Antony Etyang, Eric Bunyasi,  B Kulohoma, Kenneth Munge, T Kamau, Shanaaz Sharif, Benjamin Tsofa, E Mumbo,Ulla Griffith, Angela Brueggemann, Prof David Goldblatt, Mike English


start

START

03-11-2008
end

END

31-12-2015
QUICK DESCRIPTION

The Pneumococcal 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.

AIM

To measure the total change in Invasive Pneumococcal Disease (IPD) incidence and hospital burden following programmatic introduction of 10-valent PCV and to establish a system of longitudinal IPD surveillance to detect serotype replacement disease.





METHODOLOGY

This project proposes to evaluate the total impact of PCV use in children on IPD of both vaccine and non-vaccine types, and intends to disentangle direct from indirect effects by monitoring all individuals in a defined population (the Kilifi DSS) for both immunization events and morbidity events. It aims to define impact in terms of invasive pneumococcal disease but also in terms of more accessible public health end-points such as radiologically-confirmed pneumonia and all admissions to hospital.




OUTCOME

Disease Surveillance

last updated 15th December 2014

The lines show annual cumulative frequency curves for Invasive Pneumococcal Disease of serotypes 1, 4, 5, 6B, 7F, 9V, 14, 18C, 19F, 23F by week of year among children aged <5 years admitted to Kilifi District Hospital (KDH) who were residents of the Kilifi Health and Demographic Surveillance System. Routine immunization of children <12 months began on January 11, 2011 and the first round of catch-up vaccination took place between Jan 31-Feb 6, 2011. The year of vaccine introduction, 2011, is shown in a black thick line. Since the introduction of the catch-up campaign there has been a marked attenuation in the frequency of cases. However, the 8 baseline years show considerable variation in the number of cases year-on-year and it will take several years to be confident that changes in disease frequency are attributable to vaccine.



Disease Surveillance - All serotypes

last updated  15th December 2014

The lines show annual cumulative frequency curves for Invasive Pneumococcal Disease (All serotypes) by week of year among children aged <5 years admitted to Kilifi District Hospital (KDH) who were residents of the Kilifi Health and Demographic Surveillance System. Routine immunization of children <12 months began on January 11, 2011 and the first round of catch-up vaccination took place between Jan 31-Feb 6, 2011. The year of vaccine introduction, 2011, is shown in a black thick line.  Since the introduction of the catch-up campaign there has been a marked attenuation in the frequency of cases.  However, the 8 baseline years show considerable variation in the number of cases year-on-year and it will take several years to be confident that changes in disease frequency are attributable to vaccine



Vaccine Coverage

last updated  15th December 2014

The curves show the coverage of at least 1, at least 2 and at least 3 doses of 10-valent Pneumococcal Conjugate Vaccine calculated weekly since the beginning of 2011 among residents of Kilifi Health and Demographic Surveillance System (KHDSS) aged <5 years. The figures are derived from daily computerized returns of 26 vaccine clinics across KHDSS and weekly assessments of the population denominator of residents. At each vaccine clinic KHDSS residents are identified by querying the KHDSS population register using a computerised search and all vaccines delivered are recorded in real time. The curves present the coverage for any one week and may descend as well as ascend.



ADDITIONAL INFORMATION

The study is a collaborative project with the Division of Vaccines and Immunization and the results are expected to be used directly by DVI to determine future vaccine policy.