Surgical Mask to Prevent Influenza Transmission in Households: A Cluster Randomized Trial

Abstract

BackgroundFacemasks and respirators have been stockpiled during pandemic preparedness. However, data on their effectiveness for limiting transmission are scarce. We evaluated the effectiveness of facemask use by index cases for limiting influenza transmission by large droplets produced during coughing in households.Methodology and Principal FindingsA cluster randomized intervention trial was conducted in France during the 2008–2009 influenza season. Households were recruited during a medical visit of a household member with a positive rapid influenza A test and symptoms lasting less than 48 hours. Households were randomized either to the mask or control group for 7 days. In the intervention arm, the index case had to wear a surgical mask from the medical visit and for a period of 5 days. The trial was initially intended to include 372 households but was prematurely interrupted after the inclusion of 105 households (306 contacts) following the advice of an independent steering committee. We used generalized estimating equations to test the association between the intervention and the proportion of household contacts who developed an influenza-like illness during the 7 days following the inclusion. Influenza-like illness was reported in 24/148 (16.2%) of the contacts in the intervention arm and in 25/158 (15.8%) of the contacts in the control arm and the difference between arms was 0.40% (95%CI: −10% to 11%, P = 1.00). We observed a good adherence to the intervention. In various sensitivity analyses, we did not identify any trend in the results suggesting effectiveness of facemasks.ConclusionThis study should be interpreted with caution since the lack of statistical power prevents us to draw formal conclusion regarding effectiveness of facemasks in the context of a seasonal epidemic.Trial Registrationclinicaltrials.gov NCT00774774

Facemasks for the prevention of infection in healthcare and community settings

“…96 97 Efficacy of facemasks in the community We identified nine RCTs of facemasks in various household and community settings, [11][12][13][14][15][16][17][18][19] and in all but one they were used for respiratory protection. In one household trial the use of facemasks was tested as source control to prevent the spread of infections from the wearer.…”

“…In one household trial the use of facemasks was tested as source control to prevent the spread of infections from the wearer. 16 These RCTs had diverse settings, designs, and interventionsmany of which were mixed, such as hand washing and facemasks ( fig 2).…”

“…There was no difference between the groups (0.95, 0.44 to 2.05), and the trial was finished early owing to low recruitment and subsequent H1N1-pdm09 in fection. 16 Community use of facemasks during outbreaks and pandemics The routine use of facemasks is not recommended by WHO, the CDC, or the ECDC in the community setting. [98][99][100] However, the use of facemasks is recommended in crowded settings (such as public transport) and for those at high risk (older people, pregnant women, and those with a medical condition) during an outbreak or pandemic.…”

“…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.…”

Antiviral Face Masks for the Prevention of Influenza Infection: a Meta-analysis

“…Study titles and summaries were screened resulting in 54 studies being excluded with only nine studies remaining which met the inclusion criteria. A further two studies were excluded because the subjects were limited to residents of student dormitories and not one from Australia, 13 France, 14 Germany, 15 the U.S., 16 and Thailand, 17 respectively. All studies included all families that consisted of at least two members except the study of the U.S. that targeted only households with elementary school children.…”