Efficacy of Wolbachia-mediated sterility to suppress adult Aedes aegypti populations

Incompatible insect technique coupled with sterile insect technique (IIT-SIT) via releases of sterile male Wolbachia-infected mosquitoes is a promising tool for dengue control. In a six-year trial from 2016 to 2022, comprising 10.35 km2 of high-rise housing estates and 607,872 residents, we designed a synthetic control study methodology to assess the efficacy of IIT-SIT in reducing adult female Aedes aegypti populations, using data from a large, routinely collected, nationwide surveillance system of 57,990 unique mosquito traps in public housing estates. We demonstrated that Wolbachia-based IIT-SIT dramatically reduces wildtype Aedes aegypti populations by an average of 60.64% (95% CI: 59.59%-61.44%) and 79.37% (95% CI: 78.85%-79.87%) in 3, 6 months of releases and eventually 90.17% (95% CI: 89.92%-90.42%) in 12 and more months of releases. We further found a smaller but non-negligible suppression effect which gradually increased over time (47.91%, 95% CI: 47.29%-48.52%) in adjacent, non-intervention sites. Our results demonstrate the potential of IIT-SIT for strengthening dengue control in tropical cities, where dengue burden is the greatest.