The characteristics of households, index cases and household contacts in the three intervention groups will be compared and assessed for similarity with χ 2 tests, adjusting the comparison of household contacts for potential within-household correlation. In the primary analyses, households will only be included if the index case has laboratory-confirmed influenza infection -all other households will be dropped from the primary analysis. Furthermore, in the main study households will be dropped from the primary analysis if any of the household contacts are found to have laboratory-confirmed influenza infection at baseline although this will not be incorporated in analyses for the pilot study as per the original protocol. Therefore our results will not be biased by the potentially different transmission dynamics of other respiratory diseases compared to influenza A or B, or by the potential for more than one index case in a household when the interventions are applied.