There are about 68 clinical studies being (or have been) conducted in Guinea-Bissau. The country of the clinical trial is determined by the location of where the clinical research is being studied. Most studies are often held in multiple locations & countries.
OPV is the live attenuated vaccine against polio virus. OPV has been key in almost eradicating polio infection. Intriguingly, OPV has been associated with lower all-cause mortality and morbidity. These beneficial OPV effects were seen in contexts with no circulating polio virus and thus have nothing to do with the specific effects of OPV against polio infection. They have been coined "non-specific effects" (NSEs). Such NSEs have also been observed for other live attenuated vaccines such as BCG vaccine and measles vaccine. The underlying immunological mechanisms are unknown. Other live vaccines with beneficial NSEs have been shown to induce epigenetic changes leading to "trained immunity". They have also been associated with decreased inflammation. In the present study it will be investigates whether OPV can induce trained immunity, reduce inflammation, and induce epigenetic modifications of the innate immune cells in senior citizens in Guinea-Bissau.
In addition to protecting against measles infection, measles vaccine (MV) strengthens the individual's ability to combat infections in general - MV has beneficial non-specific effects (NSE) lowering the risk of death and admissions by around 30%. In Guinea-Bissau 30% of children do not receive a routine MV scheduled at 9 months of age, putting both the individual child's health and measles eradication at risk. WHO recommends vaccination at health system contacts, including those for curative services. At the paediatric ward of the national hospital in Guinea-Bissau, there are more than 2600 yearly contacts with measles-unvaccinated children aged 9-59 months, but no vaccines are given. In a randomised controlled trial, we will assess the effect of providing MV vs placebo to 5400 children at hospital contacts (at discharge or after an out-patient consultation) to test the hypothesis that MV reduces the risk of admission or death (composite outcome) by 25% over the subsequent 6 months.