During the first household visit, a responsible adult (usually the household head or a parent) will be asked to provide an overview of the composition of the household, and details on past illness history and influenza vaccinations (Q2, appendix). At the final household visit, the nurse will collect information (questionnaire Q4, appendix) on the overall self/proxy-reported compliance with the intervention, and on any medication taken during the follow-up period, by asking household members and also by personally checking how many masks remain unused, or how much soap or alcohol is left in the bottles and dispensers.