Secondary attack ratios of laboratory-confirmed influenza and clinical influenza in the contacts of 122 analyzed households, by intervention arm.

*Confidence intervals were calculated by the exact binomial method, not accounting for within-household correlation, and the resulting intervals may therefore slightly underestimate the uncertainty about the SARs. †By Pearson chi-square test adjusted for within-household correlation. ‡Clinical influenza definition 1 is fever≥38°C or at least 2 of headache, runny nose, sore throat, aches or pains in muscles or joints, cough, or fatigue. Clinical influenza definition 2 is at least 2 of fever≥37.8°C, cough, headache, sore throat, aches or pains in muscles or joints. Clinical influenza definition 3 is the standard CDC classification of fever≥37.8°C plus cough or sore throat.