Face Mask Use and Control of Respiratory Virus Transmission in Households

Feasibility of elementary school children's use of hand gel and facemasks during influenza season

Please cite this paper as: Allison et al. (2010) Feasibility of elementary school children’s use of hand gel and facemasks during influenza season. Influenza and Other Respiratory Viruses 4(4), 223–229.

Background  The feasibility of non‐pharmacologic interventions to prevent influenza’s spread in schools is not well known.

Objectives  To determine the acceptability of, adherence with, and barriers to the use of hand gel and facemasks in elementary schools.

Patients and Methods Intervention: We provided hand gel and facemasks to 20 teachers and their students over 4 weeks. Gel use was promoted for the first 2 weeks; mask use was promoted for the second 2 weeks. Outcomes: Acceptability, adherence, and barriers were measured by teachers’ responses on weekly surveys. Mask use was also measured by observation.

Results  The weekly survey response rate ranged from 70% to 100%. Averaged over 2 weeks, 89% of teachers thought gel use was not disruptive (week 1 – 17/20, week 2 – 16/17), 95% would use gel next winter (week 1 – 19/20, week 2 – 16/17), and 97% would use gel in a pandemic (week 1 – 20/20, week 2 – 16/17). Averaged over 2 weeks, 39% thought mask use was not disruptive (week 1 – 6/17, week 2 – 6/14), 35% would use masks next winter (week 1 – 5/17, week 2 – 6/14), and 97% would use masks in a pandemic (week 1 – 16/17, week 2 – 14/14). About 70% estimated that their students used hand gel ≥4×/day for both weeks (week 1 – 14/20, week 2 – 13/17). Students’ mask use declined over time with 59% of teachers (10/17) estimating regular mask use during week 1 and 29% (4/14) during week 2. By observation, 30% of students wore masks in week 1, while 15% wore masks in week 2. Few barriers to gel use were identified; barriers to mask use were difficulty reading facial expressions and physical discomfort.

Conclusions  Hand gel use is a feasible strategy in elementary schools. Acceptability and adherence with facemasks was low, but some students and teachers did use facemasks for 2 weeks, and most teachers would use masks in their classroom in a pandemic.

Facemasks and intensified hand hygiene in a German household trial during the 2009/2010 influenza A(H1N1) pandemic: adherence and tolerability in children and adults

Non-pharmaceutical interventions (NPI) such as facemasks and intensified hand hygiene may be effective in preventing influenza infections in households. It may be equally important that household members, especially children, can learn to use, maintain and tolerate these measures. We monitored adherence and tolerability of these NPI within a cluster-randomized trial in households with influenza index patients. We recruited 147 participants in 41 households, 39 (95%) out of 41 index patients were children (aged <14 years). In households assigned to wear facemasks, their use peaked on day 4 after symptom onset of the index patient at 73% and at 65% for children and adults, respectively. Mean daily frequency of hand disinfection in households assigned to intensified hand hygiene measures peaked at 7·7 (day 6) for children and at 10·1 (day 5) for adults. The majority of participants reported no problems with mask wearing. Data suggest that usage of NPI can be taught and that measures are well tolerated by adults and even sick children alike.

Barriers to mask wearing for influenza-like illnesses among urban Hispanic households

OBJECTIVES

To identify barriers to mask wearing and to examine the factors associated with the willingness to wear masks among households.

DESIGN AND SAMPLE

We used data sources from a study assessing the impact of 3 nonpharmaceutical interventions on the rates of influenza: exit interviews; home visits with a subset of the mask group; and a focus group.

MEASURES

Risk perception score, univariate analysis, and logistic regression were conducted to identify the characteristics and predictors of mask use. Thematic barriers to mask wearing were identified from qualitative data obtained at home visits and focus group.

RESULTS

Respondents from the mask group, when compared with the nonmask group, demonstrated higher risk perception scores concerning influenza (maximum score: 60, means: 37.6 and 30.2, p<.001) and increased perception of effectiveness of mask wearing (maximum score: 10, means: 7.8 and 7.3, p=.043). There was no significant association between demographic, attitudinal, or knowledge variables and adherence to wearing masks. Thematic barriers were identified such as social acceptability of mask use, comfort and fit, and perception of the risk/need for masks.

CONCLUSIONS

Face masks may not be an effective intervention for seasonal or pandemic influenza unless the risk perception of influenza is high. Dissemination of culturally appropriate mask use information by health authorities and providers must be emphasized when educating the public.

Attitudes of influenza-vaccinated health care workers toward masks to prevent nosocomial transmission of influenza

BACKGROUND

Influenza viruses are highly contagious. Health care workers (HCWs) are at risk of occupational exposure to influenza and may transmit the infection to their patients and coworkers.

OBJECTIVES

The aim of the study was to characterize the attitudes of HCWs regarding the use of surgical masks to prevent nosocomial influenza transmission. Furthermore, we assessed the informational needs of HCWs with regard to infection control measures.

METHODS

A survey was conducted among HCWs, using an anonymous questionnaire, at a German University Hospital during an influenza vaccination campaign.

RESULTS

Overall, 40·5% of the HCWs were vaccinated against seasonal influenza, and 35·2% were vaccinated against Influenza A/H1N1 ("swine flu"). In total, 1445 vaccinees completed the anonymous questionnaire. Of all respondents, 70·5% stated that the infection control recommendation "wearing a surgical" mask was appropriate to avoid influenza transmission. The percentage of HCWs who would like to have had more information about the infection control measures was 67·5%.

CONCLUSIONS

Appropriate interventions ought to be taken to reduce the risk of exposure to influenza viruses among HCWs. Adherence to recommendations for the use of masks among HCWs needs to be evaluated. Further work is required to highlight the informational needs of HCWs to gain an appreciation of infection control measures.

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

Background

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.

Methodology and Principal Findings

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.

Conclusion

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.

Trial Registration

clinicaltrials.gov NCT00774774

Control of influenza in healthcare settings: early lessons from the 2009 pandemic

PURPOSE OF REVIEW

The emergence of 2009 pandemic H1N1 influenza A (pH1N1) has provided a unique challenge to influenza control in healthcare settings. We provide an overview of the early lessons from the 2009 pandemic.

RECENT FINDINGS

The modes of influenza transmission and their contributions to the development of infections remain unclear. Recent studies in the guinea pig model have demonstrated airborne transmission, but data from human studies and outbreaks are inconclusive. Data on physical interventions to prevent transmission support the use of hand hygiene, gowns, gloves, face shields and respiratory protection. The effectiveness of surgical masks compared to N95 respirators has been investigated, and there is evidence from one trial that surgical masks are noninferior to N95 respirators in preventing infection. Experiences with mandatory vaccination suggest that this is a highly successful approach to increase healthcare personnel vaccination rates. Lessons from pH1N1 have multiple implications for future pandemic preparedness planning.

SUMMARY

Further research is needed on appropriate respiratory protection for influenza. Mandatory vaccination programs should be considered in all healthcare settings. Pandemic preparedness plans should be revised, focusing on flexibility, communication, stockpiling of essential supplies, and staffing support for infection control.

The effect of mask use on the spread of influenza during a pandemic

Face masks have traditionally been used in general infection control, but their efficacy at the population level in preventing transmission of influenza viruses has not been studied in detail. Data from published clinical studies indicate that the infectivity of influenza A virus is probably very high, so that transmission of infection may involve low doses of virus. At low doses, the relation between dose and the probability of infection is approximately linear, so that the reduction in infection risk is proportional to the reduction in exposure due to particle retention of the mask. A population transmission model was set up to explore the impact of population-wide mask use, allowing estimation of the effects of mask efficacy and coverage (fraction of the population wearing masks) on the basic reproduction number and the infection attack rate. We conclude that population-wide use of face masks could make an important contribution in delaying an influenza pandemic. Mask use also reduces the reproduction number, possibly even to levels sufficient for containing an influenza outbreak.

Monitoring of perceptions, anticipated behavioral, and psychological responses related to H5N1 influenza

BACKGROUND

The aim of this study was to monitor changes in behavioral and emotional responses to human H5N1 in the community over a 28-month period (from November 2005 to February 2008).

METHODS

A total of 3,527 Hong Kong Chinese adults were interviewed by telephone within the framework of six identical cross-sectional surveys carried out during the 28-month study period. Given a hypothetical scenario that two to three new human-to-human H5N1 cases had been reported in Hong Kong, the trends of the respondents in various H5N1-related risk perceptions, anticipated personal psychological responses, and anticipated personal preventive behaviors were investigated.

RESULTS

Over time, a decreased proportion of the respondents (1) felt susceptible to contracting H5N1, (2) expected a large outbreak would eventually occur, (3) believed that the impacts of H5N1 were worse than those of severe acute respiratory syndrome (SARS), and (4) anticipated adopting more types of preventive measures and experiencing mental distress in the case of a small-scale outbreak in Hong Kong (AOR from 0.27 to 0.43, p < 0.001), but the public remained vigilant on public health behaviors, such as hand-washing. The prevalence of misconceptions on the mode of transmission declined, but remained high; perceptions on the fatality of H5N1 remained largely underestimated. The SARS experience and unconfirmed beliefs about the transmission modes were associated with variables on anticipated preventive behaviors and emotional distress.

CONCLUSION

Starting in 2005 through to 2008, respondents perceived a decreasing level of susceptibility, severity, and anticipated stress towards a hypothetical human-to-human H5N1 outbreak, possibly due to the low efficiency of transmission. The public's general preparedness was still relatively good and rational, even though individual preventive behaviors were less common. However, misconceptions were prevalent among the respondents. Based on these results, public education is warranted to rectify these misconceptions.

Maintenance of influenza virus infectivity on the surfaces of personal protective equipment and clothing used in healthcare settings

Objectives

The maintenance of infectivity of influenza viruses on the surfaces of personal protective equipment and clothing is an important factor in terms of controlling viral cross-infection in the environment and preventing contact infection. The aim of this study was to determine if laboratory-grown influenza A (H1N1) virus maintained infectivity on the surfaces of personal protective equipment and clothing used in healthcare settings.

Methods

Influenza A virus (0.5 mL) was deposited on the surface of a rubber glove, an N95 particulate respirator, a surgical mask made of non-woven fabric, a gown made of Dupont Tyvek, a coated wooden desk, and stainless steel. Each sample was left for 1, 8, and 24 h, and hemagglutination (HA) and 50% tissue culture infective dose (TCID₅₀)/mL were measured.

Results

The HA titer of this influenza A virus did not decrease in any of the materials tested even after 24 h. The infectivity of influenza A virus measured by TCID₅₀ was maintained for 8 h on the surface of all materials, with the exception of the rubber glove for which virus infectivity was maintained for 24 h.

Conclusions

Our results indicate that the replacement/renewal of personal protective equipment and clothing by healthcare professionals in cases of exposure to secretions and droplets containing viruses spread by patients is an appropriate procedure to prevent cross-infection.

Protecting health care workers: a pandemic simulation based on Allegheny County

Please cite this paper as: Cooley et al. (2010) Protecting health care workers: a pandemic simulation based on Allegheny County. Influenza and Other Respiratory Viruses 4(2), 61–72.

Background and Objectives  The Advisory Committee on Immunization Practices has identified health care workers (HCWs) as a priority group to receive influenza vaccine. Although the importance of HCW to the health care system is well understood, the potential role of HCW in transmission during an epidemic has not been clearly established.

Methods  Using a standard SIR (Susceptible–Infected–Recovered) framework similar to previously developed pandemic models, we developed an agent‐based model (ABM) of Allegheny County, PA, that incorporates the key health care system features to simulate the spread of an influenza epidemic and its effect on hospital‐based HCWs.

Findings  Our simulation runs found the secondary attack rate among unprotected HCWs to be approximately 60% higher (54·3%) as that of all adults (34·1%), which would result in substantial absenteeism and additional risk to HCW families. Understanding how a pandemic may affect HCWs, who must be available to treat infected patients as well as patients with other medical conditions, is crucial to policy makers’ and hospital administrators’ preparedness planning.

Impact of non-pharmaceutical interventions on URIs and influenza in crowded, urban households

OBJECTIVES

We compared the impact of three household interventions-education, education with alcohol-based hand sanitizer, and education with hand sanitizer and face masks-on incidence and secondary transmission of upper respiratory infections (URIs) and influenza, knowledge of transmission of URIs, and vaccination rates.

METHODS

A total of 509 primarily Hispanic households participated. Participants reported symptoms twice weekly, and nasal swabs were collected from those with an influenza-like illness (ILI). Households were followed for up to 19 months and home visits were made at least every two months.

RESULTS

We recorded 5034 URIs, of which 669 cases reported ILIs and 78 were laboratory-confirmed cases of influenza. Demographic factors significantly associated with infection rates included age, gender, birth location, education, and employment. The Hand Sanitizer group was significantly more likely to report that no household member had symptoms (p < 0.01), but there were no significant differences in rates of infection by intervention group in multivariate analyses. Knowledge improved significantly more in the Hand Sanitizer group (p < 0.0001). The proportion of households that reported > or = 50% of members receiving influenza vaccine increased during the study (p < 0.001). Despite the fact that compliance with mask wearing was poor, mask wearing as well as increased crowding, lower education levels of caretakers, and index cases 0-5 years of age (compared with adults) were associated with significantly lower secondary transmission rates (all p < 0.02).

CONCLUSIONS

In this population, there was no detectable additional benefit of hand sanitizer or face masks over targeted education on overall rates of URIs, but mask wearing was associated with reduced secondary transmission and should be encouraged during outbreak situations. During the study period, community concern about methicillin-resistant Staphylococcus aureus was occurring, perhaps contributing to the use of hand sanitizer in the Education control group, and diluting the intervention's measurable impact.

Preventing the soldiers of health care from becoming victims on the pandemic battlefield: respirators or surgical masks as the armor of choice

The respiratory protective equipment necessary to protect health care workers from the novel swine-origin influenza A (H1N1) virus is not known. The knowledge gap created by this unanswered question has caused substantial debate and controversy on a global scale, leading public health organizations to feel pressured into issuing decisive recommendations despite a lack of supportive data. Changes in clinical practice caused by public health guidance during such high-profile events can be expected to establish a new standard of care. Also possible is an unforeseen gradual transition to widespread N95 respirator use, driven by public health pressures instead of science, for all outbreaks of influenza or influenza-like illness. Therefore, public health organizations and other influential institutions should take care to avoid making changes to established practice standards, if possible, unless these changes are bolstered by sound scientific evidence. Until definitive comparative effectiveness clinical trials are conducted, the answer to this question will continue to remain elusive. In the meantime, relying on ethical principles that have been substantiated over time may help guide public health and clinical decisions.

Mask use, hand hygiene, and seasonal influenza-like illness among young adults: A randomized intervention trial

Background . During the influenza A(H1N1) pandemic, antiviral prescribing was limited, vaccines were not available early, and the effectiveness of nonpharmaceutical interventions (NPIs) was uncertain. Our study examined whether use of face masks and hand hygiene reduced the incidence of influenza-like illness (ILI).

Methods . A randomized intervention trial involving 1437 young adults living in university residence halls during the 2006–2007 influenza season was designed. Residence halls were randomly assigned to 1 of 3 groups—face mask use, face masks with hand hygiene, or control— for 6 weeks. Generalized models estimated rate ratios for clinically diagnosed or survey-reported ILI weekly and cumulatively.

Results . We observed significant reductions in ILI during weeks 4–6 in the mask and hand hygiene group, compared with the control group, ranging from 35% (confidence interval [CI], 9%–53%) to 51% (CI, 13%–73%), after adjusting for vaccination and other covariates. Face mask use alone showed a similar reduction in ILI compared with the control group, but adjusted estimates were not statistically significant. Neither face mask use and hand hygiene nor face mask use alone was associated with a significant reduction in the rate of ILI cumulatively.

Conclusions . These findings suggest that face masks and hand hygiene may reduce respiratory illnesses in shared living settings and mitigate the impact of the influenza A(H1N1) pandemic.

Trial Registration . ClinicalTrials.gov identifier: NCT00490633.

Face masks to prevent transmission of influenza virus: a systematic review

Influenza viruses circulate around the world every year. From time to time new strains emerge and cause global pandemics. Many national and international health agencies recommended the use of face masks during the 2009 influenza A (H1N1) pandemic. We reviewed the English-language literature on this subject to inform public health preparedness. There is some evidence to support the wearing of masks or respirators during illness to protect others, and public health emphasis on mask wearing during illness may help to reduce influenza virus transmission. There are fewer data to support the use of masks or respirators to prevent becoming infected. Further studies in controlled settings and studies of natural infections in healthcare and community settings are required to better define the effectiveness of face masks and respirators in preventing influenza virus transmission.

Airborne transmission of disease in hospitals

Hospital-acquired infection (HAI) is an important public health issue with unacceptable levels of morbidity and mortality, over the last 5 years. Disease can be transmitted by air (over large distances), by direct/indirect contact or a combination of both routes. While contact transmission of disease forms the majority of HAI cases, transmission through the air is harder to control, but one where the engineering sciences can play an important role in limiting the spread. This forms the focus of this themed volume. In this paper, we describe the current hospital environment and review the contributions from microbiologists, mechanical and civil engineers, and mathematicians to this themed volume on the airborne transmission of infection in hospitals. The review also points out some of the outstanding scientific questions and possible approaches to mitigating transmission.