initially showed moderate levels of concern. Yet, this is visible only among households living in solid dwellings. These results suggest that the ads did not convince individuals who were unconcerned about malaria risks. Instead, they served as a reminder for those with moderate levels of awareness and concerns, prompting them to take action. At the same time, the campaign did not further change the behaviors of those who were already extremely worried about the disease. Both panels confirm the null effects for households living in non/semi-solid dwellings.

We also investigated the effects of the MNM campaign on other protective behaviors, such as wearing long-sleeve clothing and using body and wall sprays to repel mosquitoes and prevent bites. Annex Table D8 shows absence of impact on these outcomes, both overall and across dwelling type. A plausible explanation is the limited coverage that these protective behaviors received in the campaign. In fact, although the initial iteration of content discussed these actions, the ads received lower engagement compared to those on bed nets and treatment seeking. Thus, the MNM team allocated limited budget to them when the campaign was scaled-up in September-December 2021 (see Section 3.2).

Table 3: Incidence of high fever and timely help-seeking <u>(during</u> the campaign)

||A|ny member|has had|a fever|An|y membe|r sought for|help within 24h|
|---|---|---|---|---|---|---|---|---|
||(1)|(2)|(3)|(4)|(5)|(6)|(7)|(8)|
||Full|Full|Full|Solid house|Full|Full|Full|Solid house|
|T|0.007|0.008|0.016|0.008|0.006|0.019|-0.023|0.107<sup>_∗∗∗_</sup>|
||(0.017)|(0.014)|(0.018)|(0.020)|(0.030)|(0.026)|(0.040)|(0.035)|
|T _×_ Solid house|||-0.016||||0.107<sup>_∗_</sup>||
||||(0.028)||||(0.058)||
|Solid house||-0.017|-0.009|||0.051|-0.004||
|||(0.016)|(0.020)|||(0.036)|(0.046)||
|Individual controls||✓|✓|✓||✓|✓|✓|
|Cluster controls||✓|✓|✓||✓|✓|✓|
|Observations|5158|5158|5158|2381|724|724|724|301|
|Adj. R-squared|0.002|0.033|0.033|0.037|-0.000|0.034|0.038|0.021|
|Mean in control|0.156|0.156|0.156|0.145|0.797|0.797|0.797|0.808|
|SD in control|0.363|0.363|0.363|0.352|0.403|0.403|0.403|0.395|

Each observation is an individual. Responses collected from September 1, 2020 to January 31, 2021 are included and are weighted by the number of survey waves the individual completed in this period. In columns (1-4), the dependent variable takes value 1 if the respondent/family member has had a fever (100.4°F / 38°C or above) at least once in the period under consideration. In columns (5-8), the dependent variable takes value 1 if the respondent/family member with fever has sought for help within 24 hours at least once in the period under consideration. T is the treatment indicator. Solid house is a binary indicator equal to 1 if the individual lives in a dwelling made of stones, bricks, cement or concrete. State fixed-effects are included in all specifications. Individual controls include gender, age, household size, caste, education, distance to the medical center, employment and student status, religion, presence of pregnant woman in the house, ownership of bednet and air conditioner, and 5-year malaria incidence at baseline. Cluster controls are reported in Table 1. Standard errors are clustered at the district level.<sup>_∗_</sup> _p <_ 0 _._ 1,<sup>_∗∗_</sup> _p <_ 0 _._ 05, _∗∗∗ p <_ 0 _._ 01 As for response actions, participants in the experience sample were surveyed every two weeks regarding any occurrences of a fever (at or above 100.4°F / 38°C) within their family. For those who reported a fever, we recorded whether they sought medical assistance within 24 hours. Table 3 reports impacts on these events and behaviors. We do not find evidence that the treatment affected incidence of fever during the campaign (columns 1-4). Yet, we find that the probability to seek for treatment in a timely manner (i.e., within 24 hours) in case of a fever increased by more than 22