Following randomization, an immediate home visit will be scheduled (to take place within at most 36 hours, and ideally within 12 hours) to implement the intervention. During the home visit by a trained nurse, the purpose of the study will be explained to all household contacts and their consent obtained. Consent for children aged 17 years or younger will be obtained from their parents. Assent will also be obtained for children aged between 7 through 17. The nurse will then collect details on household composition, risk perceptions, attitudes and beliefs on influenza (questionnaire Q2, appendix), and take a nose swab and a throat swab from each household contact, except for asymptomatic children under the age of 2. Due to concerns about difficulties of taking nose and throat swabs from infants, for household members who are under 2 years of age only information on clinical symptoms will therefore be collected unless they are symptomatic. For participants who are symptomatic, a nose and a throat swab will be collected regardless of their age. The swabs will later be tested to confirm the absence of influenza in any household contact at baseline. The nurse will provide and describe proper use of a free tympanic thermometer, and the daily symptom diaries. Finally, the nurse will administer the standardized intervention through intensive counselling, and demonstration of proper wearing of masks or hand washing.