The pilot study will include the first two arms and a third mask-only arm (i.e. the mask intervention but not the hand hygiene intervention). For the first 100 households, we will apply an unbalanced randomisation of 2:1:1 among arms (1), (2) and (3). For the subsequent households (up to a further 100 households) we will apply an unbalanced randomisation of 8:1:1 among arms (1), (2) and (3) to allow us to extract maximum information about the transmission dynamics of influenza in the absence of non-pharmaceutical control measures. If the maximum sample size of 200 households is reached, there will be approximately 130, 35 and 35 households in arms (1), (2) and (3) respectively. Following completion of the pilot study, information derived about the characteristics of influenza transmission will be invaluable not least in validating our sample size calculation for the main study.