We will investigate the efficacy of the interventions on the SAR in multivariable logistic regression models with a generalized estimating equations approach to allow for potential within-household correlation [26] . Analysis will first be performed including only the effects of masks and hand hygiene. Further analyses will allow for the effects of potential confounders on the SAR. Confounders of the SAR that we will assess for each household contact include the age, gender, smoking status, chronic disease status, prior vaccination status, and additionally the age and gender of the corresponding index case. We will investigate the intervention effect in age/gender subgroups, although the statistical power for these analyses is unlikely to be high. We will further investigate the intervention effect in households where the intervention was applied sooner (with 36 hours) after symptom onset in the index case.