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Logo of bmjThis ArticleThe BMJ
BMJ. 2008 January 12; 336(7635): 55–56.
Published online 2007 November 27. doi:  10.1136/bmj.39406.511817.BE
PMCID: PMC2190279

Using physical barriers to reduce the spread of respiratory viruses

Martin Dawes, chair of family medicine

Handwashing and wearing masks, gloves, and gowns are highly effective

Preparing health professionals and the public for a flu pandemic has been the subject of much research worldwide, and governments and public health departments have published various recommendations over the past five years.1,2,3,4 One aspect of the clinical management of respiratory viruses—namely barrier methods to reduce transmission—is assessed in the accompanying systematic review by Jefferson and colleagues.5 This review found that handwashing and wearing masks, gloves, and gowns were effective individually in preventing the spread of severe acute respiratory syndrome, and even more effective when combined (odds ratio 0.09, 95% confidence interval 0.02 to 0.35, number needed to treat (NNT)=3, 2.66 to 4.97). The incremental effect of adding virucidals or antiseptics to normal handwashing to reduce respiratory disease was uncertain.

Because pandemic flu is such a potentially catastrophic event, governments worldwide should have commissioned such a review many years ago and not have left it to the academic community to take the lead. The academic community needs to educate governments that expert advice is not necessarily the best advice. Guidelines should be based on rigorous systematic reviews and need to be continuously updated.

Government and international websites such as the World Health Organization website on the status of pandemic flu ( are of some help in keeping health professionals up to date with the latest information. However, regularly updated evidence based guidelines containing levels of recommendation and, where possible, measures of effectiveness such as NNT would be very much more helpful to front line clinicians. Guidelines also highlight where the strength of the evidence is weak and more research is needed. We have an annually updated guideline on the management of hypertension,6 and it reflects badly on the consistency of knowledge translation that one is not available for influenza.

The messages distributed by governments about how to reduce the spread of respiratory viruses have not been shown to be wrong, although some are not supported by evidence. Jefferson and colleagues’ review will allow the effectiveness of the interventions and the strength of the evidence supporting them to be much more explicit; for example, it will be possible to add numbers needed to treat for handwashing, face masks, and gloves to advisory leaflets for health professionals.

So how does the review help clinicians in primary care? The benefit of washing hands between patients is clear (NNT=4), as is wearing masks (NNT=6), wearing gloves (NNT=5), and wearing gowns (NNT=5). So practices need to have a stock of gloves, simple masks (not necessarily of the advanced N95 make), and gowns. Applying all the recommendations described by various government guidelines7—such as isolation, segregation, transport, and identification of patients, creating emergency telephone lists of staff, and on-call cover when staff are sickmay seem daunting to a small practice or office. However, the one advantage with influenza, compared with more sporadic epidemics such as pertussis, is that the practice plan can be tried, evaluated, and modified each year.

Jefferson and colleagues point out that the quality of the trials was highly variable. We do not have enough evidence to be certain about many aspects of care for patients with suspected influenza—for example, which face mask is more cost effective within different healthcare settings. Although 336 trials on influenza have been registered on the WHO international clinical trials registry, only three trials are about reducing transmission using distancing (keeping a physical distance from patients with suspected disease) or barrier methods. The reasons for this include the lack of research capacity and funding and an emphasis on non-drug based treatments. Governments should continue to fund research to confirm the findings of this review and to investigate other areas of uncertainty that it identifies in the management of people with suspected influenza.


This article was published on on 22 November 2007


Competing interests: None declared.

Provenance and peer review: Commissioned; not externally peer reviewed.


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2. National Health Service. UK Health Departments’ influenza pandemic contingency plan. 2005.
3. American College of Physicians, Barnitz L, Berkwits M. The health care response to pandemic influenza. Ann Intern Med 2006;145:135-7. [PubMed]
4. Fiore AE, Shay DK, Haber P, Iskander JK, Uyeki TM, Mootrey G; Advisory Committee on Immunization Practices (ACIP), Centers for Disease Control and Prevention (CDC). Prevention and control of influenza. Recommendations of the Advisory Committee on Immunization Practices (ACIP), 2007. MMWR Recomm Rep 2007;56(RR-6):1-54.
5. Jefferson T, Foxlee R, Del Mar C, Dooley L, Ferroni E, Hewak B, et al. Physical interventions to interrupt or reduce the spread of respiratory viruses: systematic review. BMJ 2007. doi: 10.1136/bmj.39393.510347.BE
6. Khan NA, Hemmelgarn B, Padwal R, Larochelle P, Mahon JL, Lewanczuk RZ, et al. The 2007 Canadian hypertension education program recommendations for the management of hypertension: part 2—therapy. Can J Cardiol 2007;23:539-50. [PMC free article] [PubMed]
7. Department of Health. Infection control training material. 2007.

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