Research protocol of two concurrent cluster-randomized trials: Real-life Effect of a CAMPaign with Measles Vaccination (RECAMP-MV) and Real-life Effect of a CAMPaign with Oral Polio Vaccination (RECAMP-OPV) on mortality and morbidity among children in rural Guinea-Bissau.

BACKGROUND: Measles and oral polio vaccinations may reduce child mortality to an extent that cannot be explained by prevention of measles and polio infections; these vaccines seem to have beneficial non-specific effects. In the last decades, billions of children worldwide have received measles vaccine (MV) and oral polio vaccine (OPV) through campaigns. Meanwhile the under-five child mortality has declined. Past MV and OPV campaigns may have contributed to this decline, even in the absence of measles and polio infections. However, cessation of these campaigns, once their targeted infections are eradicated, may reverse the decline in the under-five child mortality. No randomized trial has assessed the real-life effect of either campaign on child mortality and morbidity. We present the research protocol of two concurrent trials: RECAMP-MV and RECAMP-OPV. METHODS: Both trials are cluster-randomized trials among children registered in Bandim Health Project's rural health and demographic surveillance system throughout Guinea-Bissau. RECAMP-MV is conducted among children aged 9-59 months and RECAMP-OPV is conducted among children aged 0-8 months. We randomized 222 geographical clusters to intervention or control clusters. In intervention clusters, children are offered MV or OPV (according to age at enrolment) and a health check-up. In control clusters, children are offered only a health check-up. Enrolments began in November 2016 (RECAMP-MV) and March 2017 (RECAMP-OPV). We plan 18,000 enrolments for RECAMP-MV with an average follow-up period of 18 months and 10,000 enrolments for RECAMP-OPV with an average follow-up period of 10 months. Data collection is ongoing. The primary outcome in both trials is non-accidental death or non-accidental first non-fatal hospitalization with overnight stay (composite outcome). Secondary outcomes are: non-accidental death, repeated non-fatal hospitalizations with overnight stay, cause-specific primary outcome, outpatient visit, and illness. We obtained ethical approval from Guinea-Bissau and consultative approval from Denmark. DISCUSSION: Cluster randomization and minimum risk of loss to follow-up are strengths, and no placebo a limitation. Our trials challenge the understanding that MV and OPV only prevent measles and polio, and that once both infections are eradicated, campaigns with MV and OPV can be phased out without negative implications on child health and survival. TRIAL REGISTRATION: NCT03460002.

Coverage and factors associated with receiving campaign polio vaccines in an urban population in Guinea-Bissau.

BACKGROUND: Polio eradication campaigns are intended to complement routine immunization. Studies addressing factors associated with campaign coverage are warranted to identify children missed by campaigns. METHODS: Bandim Health Project runs demographic surveillance with registration of routine immunization and campaign participation data in urban Guinea-Bissau. We assessed coverage and factors associated with receiving campaign polio vaccines in children aged 0-35 months in two polio eradication campaigns conducted in 2017 and 2018 using univariate and multivariate regression models. RESULTS: Campaign coverage reached 84% in 2017 and 88% in 2018. We found lower coverage among children of young and not formally educated mothers in univariate analyses; Children <9 months and Fula children had lower campaign coverage in both univariate and multivariate analyses. CONCLUSIONS: To increase campaign coverage in urban Guinea-Bissau attention may be directed at informing young mothers, mothers of young children, mothers without formal education, and the Fula ethnic group about campaigns.

A general measles vaccination campaign in urban Guinea-Bissau: Comparing child mortality among participants and non-participants.

BACKGROUND: Measles vaccination campaigns targeting children aged 9-59months are conducted every three years in Guinea-Bissau. Studies have demonstrated beneficial non-specific effects of measles vaccine. We compared mortality one year after the December 2012 measles vaccination campaign in Bissau city for children who received campaign measles vaccine with children who did not receive campaign measles vaccine. METHODS: Field workers from Bandim Health Project registered all children living in the Bandim Health Project's study area who received measles vaccination at the campaign posts. Children not seen during the campaign were visited at home and campaign participation status was assessed. We compared mortality rates of participants vs. non-participants in Cox regression models. RESULTS: 5633 children aged 9-59months (85%) received campaign measles vaccination and 1006 (15%) did not. During the subsequent year 16 children died. Adjusted for background factors, the hazard ratio (HR) comparing measles vaccinated versus unvaccinated was 0.28 (95% CI: 0.10-0.77). The benefit was larger for girls (HR: 0.17 (0.05-0.59)) and for children who had received routine measles vaccine before the campaign (HR: 0.15 (0.04-0.63)). CONCLUSIONS: We found indications of strong beneficial non-specific effects of receiving measles vaccine during the 2012 campaign, especially for girls and children with previous routine measles vaccination. Measles vaccination campaigns may be an effective way of improving child survival.