Findings from a household randomized controlled trial of hand washing and face masks to reduce influenza transmission in Bangkok, Thailand

Abstract

Please cite this paper as: Simmerman et al. (2011) Findings from a household randomized controlled trial of hand washing and face masks to reduce influenza transmission in Bangkok, Thailand. Influenza and Other Respiratory Viruses 5(4), 256–267 Background Evidence is needed on the effectiveness of non‐pharmaceutical interventions (NPIs) to reduce influenza transmission. Methodology We studied NPIs in households with a febrile, influenza‐positive child. Households were randomized to control, hand washing (HW), or hand washing plus paper surgical face masks (HW + FM) arms. Study nurses conducted home visits within 24 hours of enrollment and on days 3, 7, and 21. Respiratory swabs and serum were collected from all household members and tested for influenza by RT‐PCR or serology. Principal Findings Between April 2008 and August 2009, 991 (16·5%) of 5995 pediatric influenza‐like illness patients tested influenza positive. Four hundred and forty‐two index children with 1147 household members were enrolled, and 221 (50·0%) were aged <6 years. Three hundred and ninety‐seven (89·8%) households reported that the index patient slept in the parents’ bedroom. The secondary attack rate was 21·5%, and 56/345 (16·3%; 95% CI 12·4–20·2%) secondary cases were asymptomatic. Hand‐washing subjects reported 4·7 washing episodes/day, compared to 4·9 times/day in the HW + FM arm and 3·9 times/day in controls (P = 0·001). The odds ratios (ORs) for secondary influenza infection were not significantly different in the HW arm (OR = 1·20; 95% CI 0·76–1·88; P‐0.442), or the HW + FM arm (OR = 1·16; 95% CI .0·74–1·82; P = 0.525). Conclusions Influenza transmission was not reduced by interventions to promote hand washing and face mask use. This may be attributable to transmission that occurred before the intervention, poor facemask compliance, little difference in hand‐washing frequency between study groups, and shared sleeping arrangements. A prospective study design and a careful analysis of sociocultural factors could improve future NPI studies.

Facemasks for the prevention of infection in healthcare and community settings

“…The threat of pandemic A/H5N1 influenza and resultant pandemic planning drove the first RCTs of facemasks in various settings. [7][8][9][10][11][12][13][14][15][16][17][18][19] The aim of this review is to inform policy makers and stakeholders by examining and summarising the available evidence related to the efficacy of facemasks and respirators, current practice, and guidelines, as well as highlighting the gaps in evidence.…”

A Randomized Clinical Trial of Three Options for N95 Respirators and Medical Masks in Health Workers

“…Masks in community settings have no clearly proved efficacy (9)(10)(11)(12)(13)(14). In three trials, participants were randomized either to hand washing or to hand washing plus surgical masks (9,11,13), with no clear additional benefit of masks.…”

“…In three trials, participants were randomized either to hand washing or to hand washing plus surgical masks (9,11,13), with no clear additional benefit of masks. We have previously shown that masks in compliant users in the household setting reduced the risk of influenza-like illness (ILI) (12).…”

Prospective Epidemiological Evaluation of Seasonal Influenza in All Elementary Schoolchildren in Matsumoto City, Japan, in 2014/2015

“…Several community-based observational and intervention studies have attempted to evaluate the transmission and control of seasonal influenza, assessing both pharmaceutical and non-pharmaceutical interventions (6)(7)(8)(9). Despite the understanding gained from these studies, additional longitudinal epidemiological studies are required to assess the spread of influenza virus (10).…”