The role of facemasks and hand hygiene in the prevention of influenza transmission in households: results from a cluster randomised trial; Berlin, Germany, 2009-2011

Abstract

BackgroundPrevious controlled studies on the effect of non-pharmaceutical interventions (NPI) - namely the use of facemasks and intensified hand hygiene - in preventing household transmission of influenza have not produced definitive results. We aimed to investigate efficacy, acceptability, and tolerability of NPI in households with influenza index patients.MethodsWe conducted a cluster randomized controlled trial during the pandemic season 2009/10 and the ensuing influenza season 2010/11. We included households with an influenza positive index case in the absence of further respiratory illness within the preceding 14 days. Study arms were wearing a facemask and practicing intensified hand hygiene (MH group), wearing facemasks only (M group) and none of the two (control group). Main outcome measure was laboratory confirmed influenza infection in a household contact. We used daily questionnaires to examine adherence and tolerability of the interventions.ResultsWe recruited 84 households (30 control, 26 M and 28 MH households) with 82, 69 and 67 household contacts, respectively. In 2009/10 all 41 index cases had a influenza A (H1N1) pdm09 infection, in 2010/11 24 had an A (H1N1) pdm09 and 20 had a B infection. The total secondary attack rate was 16% (35/218). In intention-to-treat analysis there was no statistically significant effect of the M and MH interventions on secondary infections. When analysing only households where intervention was implemented within 36 h after symptom onset of the index case, secondary infection in the pooled M and MH groups was significantly lower compared to the control group (adjusted odds ratio 0.16, 95% CI, 0.03-0.92). In a per-protocol analysis odds ratios were significantly reduced among participants of the M group (adjusted odds ratio, 0.30, 95% CI, 0.10-0.94). With the exception of MH index cases in 2010/11 adherence was good for adults and children, contacts and index cases.ConclusionsResults suggest that household transmission of influenza can be reduced by the use of NPI, such as facemasks and intensified hand hygiene, when implemented early and used diligently. Concerns about acceptability and tolerability of the interventions should not be a reason against their recommendation.Trial registrationThe study was registered with ClinicalTrials.gov (Identifier NCT00833885).

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.…”

“…However, the risk of influenza was significantly lower if the data from two intervention arms were pooled and the intervention was applied within 36 hours of the onset of symptoms (odds ratio 0.16, 0.03 to 0.92). 19 A household trial in France examined the role of medical masks as source control-index patients were randomised into medical mask (52 household and 148 contacts) and control groups (53 household and 158 contacts). 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.…”

“…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.…”

Hand hygiene to reduce community transmission of influenza and acute respiratory tract infection: a systematic review

“…Three newer cluster randomised trials with influenza and influenza-like illness as outcomes were not eligible for inclusion as they examined the effect of hand hygiene only in combination with facemask use. All three studies (two in university halls of residence in the USA 38,39 and one of secondary transmission in German households 40 ) suggested a reduction in influenza and ⁄ or ILI in groups receiving hand hygiene and facemasks compared with controls but results were generally not statistically significant. A recently published cluster randomised trial 41 of regular hand sanitiser use on ILI absence in Thai pre-schools was not eligible for inclusion because insufficient data were presented on ILI episodes to allow an effect measure to be calculated.…”

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.…”