A key theme of research of the Epidemiology and Demography Department is vaccine programme design and evaluation.  Many of our community based epidemiological studies are directly related to this research, for example studies of nasopharyngeal carriage of Streptococcus pneumoniae (Spn), and household transmission of respiratory viruses (link to community research). Similarly, denominator based estimates of disease incidence provided by the link between the hospital admissions and the Kilifi Health and Demographic Surveillance System (KHDSS) underpins this work (link to KHDSS research). 

Data collected in this way supports mathematical modelling to simulate the potential impact of different immunization strategies. An example, is that of respiratory syncytial virus (RSV), where work has focused on assessing the potential to control disease by vaccinating outside the age group primarily associated with severe disease, ie 1-3 month olds. 

In another example, the potential effect of vaccination on the distribution of vaccine and non-vaccine serotypes of Spn is being modelled to predict the possible effects of vaccination on serotype replacement.  Past work which tracked the incidence of Heamophilus influenzae type B (Hib), and coverage, following vaccine introduction, was influential in Ministry of Health assessment of vaccine benefit.  The framework provided by the KHDSS is being currently being used to support a large-scale evaluation of the impact of Spn conjugate vaccine, introduced countrywide in 2011 (PCVIS). 

Future research 
The KHDSS will continue to develop as a site to support vaccine trials (eg proposed RSV and group B streptococcus vaccine) and interventions, such as rotavirus and, perhaps, malaria vaccination.  This will adopt the framework set up by the Pneumococcal Conjugate Vaccine Impact Study (PCVIS). Rotavirus vaccination evaluation is just starting following its introduction in July 2014. 

Key questions to address in all such studies are (i) how much indirect protection is afforded to those not directly protected by vaccine (Ifedayo Adetifa) and (ii) how does vaccination influence serotype/genotype distribution and what are the implications to effectiveness (Betty Owor).