Fig 1.
Deployment of wMel across Medellín, Bello and Itagüí—combining pragmatic staged (Bello and Medellín) and municipality-wide (Itagüí) deployments (dark blue, blue and yellow) with a case-control study with test-negative design in a focused study area of intervention (orange) and untreated (green) areas (produced in QGIS version 3.28.3 using administrative boundaries freely available from the municipal governments of Bello (https://www.datos.gov.co/Ordenamiento-Territorial/Divisi-n-Pol-tico-Administrativa-Barrios-Bello-Ant/pnhh-ccwd), Medellín (https://www.medellin.gov.co/geomedellin/datosAbiertos/1043), and Itagüí (https://www.datos.gov.co/Ordenamiento-Territorial/Localizaci-n-Geogr-fica-de-los-Barrios-del-Municip/didi-drqa)).
Table 1.
Baseline characteristics and release summary by area in the case-control study area.
Fig 2.
Dengue incidence in wMel-release areas in A) Bello, B) Medellín and C) Itagüí.
Dark blue line is the monthly incidence of dengue case notifications per 100,000 population (left-hand Y axis; note different scale among graphs) from January 2008 (Itagüí)/2009 (Medellín)/2010 (Bello) to June 2023. Light blue shading indicates the wMel area coverage (km2) in partially wMel-treated areas (wMel releases were ongoing or completed but not stably at ≥60% wMel), and darker blue shading indicates the wMel area coverage (km2) in fully wMel-treated areas (releases were completed and stably at ≥60% wMel) (right-hand Y axis).
Fig 3.
Efficacy of the wMel intervention against suspected dengue notified to the routine disease surveillance system in the partially or fully wMel-treated period compared to the untreated period.
Point estimates (symbols) and 95% confidence intervals (horizontal bars) from interrupted time series analysis of monthly dengue case notifications to the routine surveillance system. Efficacy is expressed as 100x(1-IRR). wMel exposure was defined as ‘untreated’ prior to wMel releases, ‘partially treated’ if wMel releases were ongoing or completed but not stably at ≥60% wMel, and ‘fully treated’ if releases were completed and stably at ≥60% wMel.
Fig 4.
Efficacy of the wMel intervention against suspected dengue notified to the routine disease surveillance system by categorised level of commune-level (Bello and Medellín) or city-level (Itagüí) wMel prevalence.
Point estimates (symbols) and 95% confidence intervals (horizontal bars) from interrupted time series analysis of monthly dengue case notifications to the routine surveillance system. Efficacy is expressed as 100x(1-IRR).
Fig 5.
Annualised dengue incidence per 100,000 population in 57 dengue-endemic Colombian cities with population >100,000, 2008 to June 2023.
Coloured filled circles indicate annual dengue incidence in the three cities in the Aburrá Valley where staged roll-out of the wMel intervention was implemented between 2017 and 2021: Bello (orange), Medellín (blue) and Itagüí (green). Open grey circles represent annual dengue incidence in the remaining 54 cities (note the log10 scale on the Y-axis). The horizontal lines indicate the median and interquartile range of dengue incidence among the 57 cities in each year. The vertical dashed line roughly demarcates the pre-intervention and post-intervention periods.
Fig 6.
Efficacy in the case-control study intention-to-treat analysis.
Shown is the protective efficacy (expressed as 100×(1−OR)) of wMel-infected Aedes aegypti deployments against virologically-confirmed dengue of any serotype (VCD), serotype 1 dengue (DENV1), and VCD and presumptive dengue (any dengue).
Fig 7.
Percentage efficacy of the wMel intervention against (A) virologically-confirmed dengue and (B) VCDs and presumptive dengue cases (any dengue) according to Wolbachia exposure index.
Markers show stratum-specific efficacy (and 95% confidence intervals) against dengue by categorised level of Wolbachia exposure index, with WEI based on duration-weighted wMel frequencies in the cluster of residence and other visited locations (open circles) or wMel frequency in cluster of residence only (closed circles).