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NCT ID: NCT06266754 Enrolling by invitation - Vaccine Reaction Clinical Trials

The Non-Specific Immunological Effects of Providing Oral Polio Vaccine to Seniors in Guinea-Bissau

Start date: January 29, 2024
Phase: Phase 4
Study type: Interventional

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.

NCT ID: NCT04220671 Enrolling by invitation - Mortality Clinical Trials

Measles Vaccination at Health System Contacts

Start date: January 8, 2020
Phase: Phase 4
Study type: Interventional

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.