and Health Survey (India IIPS, 2022), indicating that only around a third of households in India possess at least one mosquito net, with an estimated 8% having an insecticide-treated mosquito net (ITN). In the three study states, population-level estimates suggest that only one in three women and six in ten men have accessed the internet at some point. These statistics emphasize that our study and evaluated intervention reflect the results from a specific subgroup of the population, and do not generalize to individuals and households without access to the internet.

As anticipated, both covariates and pre-treatment outcomes vary among different types of dwellings. Annex Tables D5 and D6 demonstrate that households residing in solid dwellings exhibit greater economic advantages, such as higher levels of education, lower unemployment rates, and belonging to higher castes. Additionally, they tend to reside in closer proximity to urban centers with medical facilities and are less prone to experiencing malaria in the last 5 years and 2 weeks compared to those living in non/semi-solid dwellings. Although bed net ownership rates are comparable between the two groups, residents in solid dwellings are less inclined to use bed nets consistently. This could be attributed to their perception of lower malaria contraction risks. These differences emphasize the importance of having both types of dwellers equally represented in our sample, which allows us to explore potential effect heterogeneity.

# **5.2 Survey-based Results**

## **5.2.1 Preventative behaviors and response actions during the campaign**

Table 2 reports the results on sleeping under mosquito nets during the campaign, one of the main messages of the ads that received more budget. Columns (1-4) pertain to the respondent’s behavior, while columns (5-8) capture the behavior of the entire household. When considering the complete sample (of respondents that had at least one bed net), we note modest yet favorable impacts of the campaign on increased bed net utilization in columns (1-2) and (5-6). Individually, there is an approximate increase of 3 percentage points (p.p.) in usage (5% relative to control), and for the entire households, there is an increase of 2.8 p.p. (4% relative to control). In columns (3) and (7) we report heterogeneous treatment effects across dwelling type, which reveal that the previous results are solely driven by solid dwellers. Specifically, in solid houses (columns 4 and 8), our estimates indicate that the campaign improved the frequency of bed net use at the individual level by 5.5 p.p. (or 9% relative to control), and increased the share of family members using bed nets by almost 7 p.p. (or 11%). Note that these effects are unlikely to be driven by differential bed net ownership rates across dwelling type, as only households with at least one bed net are considered in the analysis. Moreover, Annex Tables D5 and D6 show a balance across dwelling type in terms of bed net ownership rates and number of bed nets per family member (i.e., approximately one for every two individuals).<sup>33</sup>

> Figure 3 reports the heterogeneous treatment effects of the campaign on bed net use throughout the campaign period (left panel) and across baseline risk perceptions levels (right panel). The

> 33The price of a basic bed mosquito net in India ranges from $1.5 to $5, making them affordable for a significant portion of the population.

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