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Surgical mask to prevent influenza transmission in households: a cluster randomized trial.

ABSTRACT: Facemasks 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.A 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.This 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.clinicaltrials.gov NCT00774774.

SUBMITTER: Canini L

PROVIDER: S-EPMC2984432 | biostudies-literature | 2010 Nov

REPOSITORIES: biostudies-literature

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Surgical mask to prevent influenza transmission in households: a cluster randomized trial.

Canini Laetitia L Andréoletti Laurent L Ferrari Pascal P D'Angelo Romina R Blanchon Thierry T Lemaitre Magali M Filleul Laurent L Ferry Jean-Pierre JP Desmaizieres Michel M Smadja Serge S Valleron Alain-Jacques AJ Carrat Fabrice F

PloS one 20101117 11

<h4>Background</h4>Facemasks 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.<h4>Methodology and principal findings</h4>A cluster randomized intervention trial was conducted in France during the 2008-2009 influenza season. Households were recruited du ...[more]

PMID: 21103330

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Project description:BackgroundThere are sparse data on whether non-pharmaceutical interventions can reduce the spread of influenza. We implemented a study of the feasibility and efficacy of face masks and hand hygiene to reduce influenza transmission among Hong Kong household members.Methodology/principal findingsWe conducted a cluster randomized controlled trial of households (composed of at least 3 members) where an index subject presented with influenza-like-illness of <48 hours duration. After influenza was confirmed in an index case by the QuickVue Influenza A+B rapid test, the household of the index subject was randomized to 1) control or 2) surgical face masks or 3) hand hygiene. Households were visited within 36 hours, and 3, 6 and 9 days later. Nose and throat swabs were collected from index subjects and all household contacts at each home visit and tested by viral culture. The primary outcome measure was laboratory culture confirmed influenza in a household contact; the secondary outcome was clinically diagnosed influenza (by self-reported symptoms). We randomized 198 households and completed follow up home visits in 128; the index cases in 122 of those households had laboratory-confirmed influenza. There were 21 household contacts with laboratory confirmed influenza corresponding to a secondary attack ratio of 6%. Clinical secondary attack ratios varied from 5% to 18% depending on case definitions. The laboratory-based or clinical secondary attack ratios did not significantly differ across the intervention arms. Adherence to interventions was variable.Conclusions/significanceThe secondary attack ratios were lower than anticipated, and lower than reported in other countries, perhaps due to differing patterns of susceptibility, lack of significant antigenic drift in circulating influenza virus strains recently, and/or issues related to the symptomatic recruitment design. Lessons learnt from this pilot have informed changes for the main study in 2008.Trial registrationClinicalTrials.gov NCT00425893 HKClinicalTrials.com HKCTR-365.

Project description:BackgroundSince the 2008 inception of universal childhood influenza vaccination, national rates have risen more dramatically among younger children than older children and reported rates across racial/ethnic groups are inconsistent. Interventions may be needed to address age and racial disparities to achieve the recommended childhood influenza vaccination target of 70%.PurposeTo evaluate an intervention to increase childhood influenza vaccination across age and racial groups.MethodsIn 2011-2012, a total of 20 primary care practices treating children were randomly assigned to the intervention and control arms of a cluster randomized controlled trial to increase childhood influenza vaccination uptake using a toolkit and other strategies including early delivery of donated vaccine, in-service staff meetings, and publicity.ResultsThe average vaccination differences from pre-intervention to the intervention year were significantly larger in the intervention arm (n=10 practices) than the control arm (n=10 practices); for children aged 9-18 years (11.1 pct pts intervention vs 4.3 pct pts control, p<0.05); for non-white children (16.7 pct pts intervention vs 4.6 pct pts control, p<0.001); and overall (9.9 pct pts intervention vs 4.2 pct pts control, p<0.01). In multi-level modeling that accounted for person- and practice-level variables and the interactions among age, race, and intervention, the likelihood of vaccination increased with younger age group (6-23 months); white race; commercial insurance; the practice's pre-intervention vaccination rate; and being in the intervention arm. Estimates of the interaction terms indicated that the intervention increased the likelihood of vaccination for non-white children in all age groups and white children aged 9-18 years.ConclusionsA multi-strategy intervention that includes a practice improvement toolkit can significantly improve influenza vaccination uptake across age and racial groups without targeting specific groups, especially in practices with large percentages of minority children.

Project description:BACKGROUND: Previous 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. METHODS: We 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. RESULTS: We 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. CONCLUSIONS: Results 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 REGISTRATION: The study was registered with ClinicalTrials.gov (Identifier NCT00833885).

Project description:BackgroundObservational evidence suggests that mask wearing mitigates transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It is uncertain if this observed association arises through protection of uninfected wearers (protective effect), via reduced transmission from infected mask wearers (source control), or both.ObjectiveTo assess whether recommending surgical mask use outside the home reduces wearers' risk for SARS-CoV-2 infection in a setting where masks were uncommon and not among recommended public health measures.DesignRandomized controlled trial (DANMASK-19 [Danish Study to Assess Face Masks for the Protection Against COVID-19 Infection]). (ClinicalTrials.gov: NCT04337541).SettingDenmark, April and May 2020.ParticipantsAdults spending more than 3 hours per day outside the home without occupational mask use.InterventionEncouragement to follow social distancing measures for coronavirus disease 2019, plus either no mask recommendation or a recommendation to wear a mask when outside the home among other persons together with a supply of 50 surgical masks and instructions for proper use.MeasurementsThe primary outcome was SARS-CoV-2 infection in the mask wearer at 1 month by antibody testing, polymerase chain reaction (PCR), or hospital diagnosis. The secondary outcome was PCR positivity for other respiratory viruses.ResultsA total of 3030 participants were randomly assigned to the recommendation to wear masks, and 2994 were assigned to control; 4862 completed the study. Infection with SARS-CoV-2 occurred in 42 participants recommended masks (1.8%) and 53 control participants (2.1%). The between-group difference was -0.3 percentage point (95% CI, -1.2 to 0.4 percentage point; P = 0.38) (odds ratio, 0.82 [CI, 0.54 to 1.23]; P = 0.33). Multiple imputation accounting for loss to follow-up yielded similar results. Although the difference observed was not statistically significant, the 95% CIs are compatible with a 46% reduction to a 23% increase in infection.LimitationInconclusive results, missing data, variable adherence, patient-reported findings on home tests, no blinding, and no assessment of whether masks could decrease disease transmission from mask wearers to others.ConclusionThe recommendation to wear surgical masks to supplement other public health measures did not reduce the SARS-CoV-2 infection rate among wearers by more than 50% in a community with modest infection rates, some degree of social distancing, and uncommon general mask use. The data were compatible with lesser degrees of self-protection.Primary funding sourceThe Salling Foundations.

Dataset Information

Surgical mask to prevent influenza transmission in households: a cluster randomized trial.

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Surgical mask to prevent influenza transmission in households: a cluster randomized trial.

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