A peer group intervention implemented by community volunteers increased HIV prevention knowledge

BACKGROUND: HIV prevention knowledge levels are low in sub-Saharan Africa. In our efficacy study, the Mzake ndi Mzake (Friend-to-Friend; hereafter Mzake) 6-session peer group intervention, delivered by health workers, improved HIV prevention knowledge and other outcomes in Malawi. To expand HIV prevention approaches, this implementation study tested whether the intervention remained effective when implemented by trained community volunteers. HIV prevention knowledge findings are presented. METHODS: Using a stepped wedge design, three communities implemented the Mzake program sequentially in randomly assigned order. Repeated surveys assessed outcomes, and participants served as controls until they completed the program. At Time 2, Community 1 became the intervention group, and at Time 3, Communities 1 and 2 were the intervention group. HIV prevention knowledge, the primary outcome, was assessed through two indicators: UNAIDS comprehensive knowledge (UNAIDS Knowledge), defined as correctly answering five HIV prevention questions (Yes/No), and a 9-item HIV/PMTCT Knowledge Index (number correct). Multivariate generalized estimating equation logistic regression (UNAIDS Knowledge) and mixed-effects regression models (HIV/PMTCT Knowledge Index) were used to assess knowledge controlling for five sociodemographic factors. RESULTS: In bivariate analyses of UNAIDS Knowledge, more persons answered correctly in the intervention group than the control group at Time 2 (56.8% vs. 47.9%, p < 0.01), but the difference was not significant at Time 3. In logistic regression, there was a significant linear increase in the proportion who correctly answered all questions in the control group, but the increase was significantly higher in the intervention group (log-odds estimate = 0.17, SE = 0.06, p-value < 0.01). The HIV/PMTCT Knowledge Index scores increased over time for both groups, but in the intervention group the increase was significantly higher than the control group (0.11 at Time 2; 0.21 at Time 3). In youth and adult subsamples analyses, the intervention was highly effective in increasing knowledge for youth, but not for adults. CONCLUSION: This implementation study showed that Mzake was effective in increasing HIV prevention knowledge when delivered by community members. Community approaches offer an important strategy to increase HIV prevention in rural communities without burdening healthcare systems. TRIAL REGISTRATION: ClinicalTrials.gov NCT02765659. Registered 06/05/2016 SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12889-022-14715-3.