Observational studies of health interventions in Guinea-Bissau and other low-income settings
Observational studies of vaccines and VAS are ongoing in Guinea-Bissau and at several health and demographic surveillance (HDSS) sites in low-income countries54. With DANIDA and EU funding, we have established a vaccine network consisting of sites in Guinea-Bissau, Ghana (2 sites), Burkina Faso, Kenya and India. A PhD student from each of the sites is responsible for the collection and analysis of vaccine and VAS data. Several new interventions (pneumococcal and rotavirus vaccines) are under implementation with more in the pipeline (e.g. malaria vaccine). We will assess sex-differential and NSEs of these interventions e.g. by comparing mortality before and after the introduction or taking advantage of step-wise introduction. Interactions with existing health interventions will also be examined, e.g. if the effect depends on the sequence of vaccines.
In Guinea-Bissau we have conducted several studies of the NSEs of smallpox vaccine. Our studies suggest that a smallpox vaccine scar is associated with lower adult mortality20,21 and reduces the risk of HIV infection significantly for women (unpublished data). Preliminary data from a cohort of HIV-infected patients in Bissau suggest that a smallpox scar increases the time to anti-retroviral treatment (ART). The results support that smallpox vaccine has a general immuno-modulatory effect. We will explore whether smallpox vaccination is associated with reduced prevalence of TB and other chronic diseases with a suspected inflammation pathogenesis, e.g. metabolic syndrome.
Estimates of the effect on overall mortality of introducing new vaccines or changing the sequence of vaccines in low-income countries. Estimates of the effect of smallpox vaccination on the incidence of HIV, the outcome of HIV, time to ART as well as on TB and markers of metabolic syndrome.
The observational studies will define the most promising future RCTs to change policy and reduce child mortality (Figure 1). Showing beneficial NSEs will not lead to reintroduction of smallpox vaccine but will greatly strengthen the case for NSEs.
The study protocols will be submitted for approval to the relevant ethical committees.