Effectiveness of NPIs for Flu Table 1. Characteristics of 198 randomized index subjects by intervention arm; the 128 index subjects successfully followed with home visits and their 370 household contacts. Control Randomized (n = 127) Face mask Randomized (n = 35) Followed up (n = 74) Followed up (n = 22) Hand hygiene Randomized (n = 36) Followed up (n = 32) Index subjects Age group (%) 2–15 years 16–30 years 31–50 years 50+ years No. (%) men Symptoms (%) Cough Runny nose Fatigue / tiredness Fever (body temperature$38uC) Headache Sore throat Household contacts Age group (%) 0–24 hours 24–48 hours 48+ hours 0–15 years 16–30 years 31–50 years 50+ years Aches / pains in muscles or 62 (49%) joints Onset to randomization interval (%) No. (%) men Influenza vaccination in the previous 12 months doi:10.1371/journal.pone.0002101.t001 48 (38%) 23 (18%) 32 (25%) 24 (19%) 60 (47%) 99 (78%) 98 (77%) 96 (76%) 94 (74%) 80 (63%) 69 (54%) 86 (68%) 35 (28%) 5 (4%) – – – – – – – – – – – – 33 (45%) 10 (14%) 17 (23%) 14 (19%) 32 (43%) 62 (84%) 61 (82%) 56 (76%) 54 (73%) 40 (54%) 37 (50%) 34 (46%) 48 (65%) 22 (30%) 4 (5%) (n = 213) 32 (15%) 43 (20%) 92 (43%) 43 (20%) 83 (39%) 29 (14%) 12 (34%) 7 (20%) 11 (31%) 5 (14%) 16 (46%) 24 (69%) 28 (80%) 26 (74%) 25 (71%) 29 (83%) 23 (66%) 18 (51%) 21 (60%) 12 (34%) 1 (3%) – – – – – – – – – – – – 9 (41%) 3 (14%) 6 (27%) 4 (18%) 12 (55%) 13 (59%) 16 (73%) 16 (73%) 17 (77%) 18 (82%) 13 (59%) 9 (41%) 14 (64%) 8 (36%) 0 (0%) (n = 65) 11 (17%) 13 (20%) 28 (43%) 12 (18%) 26 (40%) 3 (1%) 13 (36%) 7 (19%) 10 (28%) 6 (17%) 14 (39%) 33 (92%) 28 (78%) 29 (81%) 29 (81%) 22 (61%) 22 (61%) 18 (50%) 25 (69%) 7 (19%) 3 (8%) – – – – – – – – – – – – 12 (38%) 6 (19%) 10 (31%) 4 (12%) 12 (38%) 29 (91%) 26 (81%) 25 (78%) 27 (84%) 19 (59%) 19 (59%) 16 (50%) 22 (69%) 7 (22%) 3 (9%) (n = 92) 14 (15%) 17 (18%) 35 (38%) 25 (27%) 37 (40%) 12 (6%) (household contacts) in the hand hygiene arm reported washing their hands often or always after sneezing, coughing or cleaning their nose compared to 31% (27%) and 63% (47%) in the control and face mask arms. In the hand hygiene group, households used a median of 56 g (IQR: 27 g, 93 g) of alcohol from the automatic sanitizer, and a median of 88 g (IQR: 63 g, 149 g) of liquid hand soap, while regarding the individual bottles of alcohol hand rub index subjects used a median of 7 g (IQR: 2 g, 13 g) and household contacts used a median of 5 g (IQR: 1 g, 12 g). Adverse events There were no reported adverse events, including allergic reactions to the intervention measures or other conditions requiring medical attention. Discussion If an influenza pandemic emerges, the likely limited supply of antivirals and vaccines will mean that non-pharmaceutical interventions have a major role to play in mitigating disease spread [11,12]. While conventional wisdom proposes that hand hygiene [8], and perhaps surgical masks [26], could be effective measures to reduce household transmission of influenza, all available data have so far been derived from at best observational settings and mostly based on anecdotal evidence rather than controlled trials [7,8,27]. Our study is the first reported community-based randomized trial of these interven- tions specifically against influenza, with laboratory-confirmed outcomes. Strengths of our study design include the randomized allocation of interventions, the laboratory-based outcome measures, and our demonstrated ability to observe secondary infections with the implied potential to detect reduction in secondary attack ratios. Whereas the present study was not powered to assess the relative efficacy of the interventions, it has proved successful in demonstrating the feasibility of our study design and the local characteristics of influenza transmission. The present findings have facilitated the planning of a subsequent larger study, described in more detail in Protocol S1. PLoS ONE | www.plosone.org 5 May 2008 | Volume 3 | Issue 5 | e2101