Results
REGRESSION
On average, by day 22 from the initial invitation, the invitation letters including an animation video produced a slightly lower overall response proportion (37.7%) compared to the generic invitation letters without an animation video (38.5%) (OR: 0.97; 95% CI: 0.95–0.99) (Table 
Response proportion (by day 22 and by the end of the survey, respectively) for intervention and control groups. Percent (descriptive) and OR (logistic regression)Intervention group 1 A:Animation targeted ethnic minoritiesIntervention group 1B:Animation targeted the general population (general video)Intervention group 2 A:Animation targeted men aged 16–24 years1.13(1.02–1.26)*Intervention group 2B:Animation targeted the general population (general video)Intervention group 3 A:Animation targeted women aged 75 years or olderIntervention group 3B:Animation targeted the general population (general video)Intervention group 4:Animation targeted the general population (general video)The three targeted animation videos to specific subgroups tended to produce higher response proportions compared to the non-targeted animation video (Table 
Response proportion (by day 22 and by the end of the survey, respectively) and OR of response by animation video (targeted animation video vs. general animation video). Percent (descriptive) and OR (logistic regression)Intervention group 2 A:Animation targeted men aged 16–24 yearsIntervention group 2B:Animation targeted the general population (general video)Intervention group 3 A:Animation targeted women aged 75 years or olderIntervention group 3B:Animation targeted the general population (general video)Looking at the demographic variables and urbanization, generally no overall effect of the intervention with animation videos was seen on response proportion by the end of the survey in most subgroups (Table 
Overall Response proportion comparing intervention and control group by sociodemographic variables by the end of survey. Percent (descriptive) and OR (logistic regression)