Published 22 September 2009, doi:10.1136/bmj.b3675
Cite this as: BMJ 2009;339:b3675

Research

Physical interventions to interrupt or reduce the spread of respiratory viruses: systematic review

¹ Acute Respiratory Infections Group, Cochrane Collaboration, Rome, Italy, ² Faculty of Health Sciences and Medicine, Bond University, Gold Coast, Australia, ³ Department of General Practice and Primary Health Care, Ghent University, Belgium, ⁴ Department of Family and Community Medicine, College of Medicine, King Saud University, Riyadh, Saudi Arabia, ⁵ Department of Clinical Pharmacy and King Khalid University Hospital, King Saud University, Riyadh, Saudi Arabia, ⁶ Department of Health Sciences, University of York, York, ⁷ Cochrane Vaccines Field, Azienda Sanitaria Locale, Alessandria, Italy

Objective To review systematically the evidence of effectiveness of physical interventions to interrupt or reduce the spread of respiratory viruses.

Data sources Cochrane Library, Medline, OldMedline, Embase, and CINAHL, without restrictions on language or publication.

Data selection Studies of any intervention to prevent the transmission of respiratory viruses (isolation, quarantine, social distancing, barriers, personal protection, and hygiene). A search of study designs included randomised trials, cohort, case-control, crossover, before and after, and time series studies. After scanning of the titles, abstracts and full text articles as a first filter, a standardised form was used to assess the eligibility of the remainder. Risk of bias of randomised studies was assessed for generation of the allocation sequence, allocation concealment, blinding, and follow-up. Non-randomised studies were assessed for the presence of potential confounders and classified as being at low, medium, or high risk of bias.

Data synthesis 58 papers of 59 studies were included. The quality of the studies was poor for all four randomised controlled trials and most cluster randomised controlled trials; the observational studies were of mixed quality. Meta-analysis of six case-control studies suggested that physical measures are highly effective in preventing the spread of severe acute respiratory syndrome: handwashing more than 10 times daily (odds ratio 0.45, 95% confidence interval 0.36 to 0.57; number needed to treat=4, 95% confidence interval 3.65 to 5.52), wearing masks (0.32, 0.25 to 0.40; NNT=6, 4.54 to 8.03), wearing N95 masks (0.09, 0.03 to 0.30; NNT=3, 2.37 to 4.06), wearing gloves (0.43, 0.29 to 0.65; NNT=5, 4.15 to 15.41), wearing gowns (0.23, 0.14 to 0.37; NNT=5, 3.37 to 7.12), and handwashing, masks, gloves, and gowns combined (0.09, 0.02 to 0.35; NNT=3, 2.66 to 4.97). The combination was also effective in interrupting the spread of influenza within households. The highest quality cluster randomised trials suggested that spread of respiratory viruses can be prevented by hygienic measures in younger children and within households. Evidence that the more uncomfortable and expensive N95 masks were superior to simple surgical masks was limited, but they caused skin irritation. The incremental effect of adding virucidals or antiseptics to normal handwashing to reduce respiratory disease remains uncertain. Global measures, such as screening at entry ports, were not properly evaluated. Evidence was limited for social distancing being effective, especially if related to risk of exposure—that is, the higher the risk the longer the distancing period.

Conclusion Routine long term implementation of some of the measures to interrupt or reduce the spread of respiratory viruses might be difficult. However, many simple and low cost interventions reduce the transmission of epidemic respiratory viruses. More resources should be invested into studying which physical interventions are the most effective, flexible, and cost effective means of minimising the impact of acute respiratory tract infections.

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited, the use is non commercial and is otherwise in compliance with the license. See: http://creativecommons.org/licenses/by-nc/2.0/ and http://creativecommons.org/licenses/by-nc/2.0/legalcode.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    StumbleUpon    Technorati    What's this?

Relevant Articles

Relation of study quality, concordance, take home message, funding, and impact in studies of influenza vaccines: systematic review

T Jefferson, C Di Pietrantonj, M G Debalini, A Rivetti, and V Demicheli
BMJ 2009 338: b354. [Abstract] [Full Text] [PDF]

Physical interventions to interrupt or reduce the spread of respiratory viruses: systematic review

Tom Jefferson, Ruth Foxlee, Chris Del Mar, Liz Dooley, Eliana Ferroni, Bill Hewak, Adi Prabhala, Sree Nair, and Alex Rivetti
BMJ 2008 336: 77-80. [Abstract] [Full Text] [PDF]

Measuring inconsistency in meta-analyses

Julian P T Higgins, Simon G Thompson, Jonathan J Deeks, and Douglas G Altman
BMJ 2003 327: 557-560. [Extract] [Full Text] [PDF]

Related external webpages:

Listen to a podcast interview with Tom Jefferson

This article has been cited by other articles:

• Gerberding, J. L. (2009). Influenza in 2009: New Solutions, Same Old Problems. JAMA 302: 1907-1908 [Full text]  
• Srinivasan, A., Perl, T. M. (2009). Respiratory Protection Against Influenza. JAMA 302: 1903-1904 [Full text]  

Rapid Responses:

Read all Rapid Responses

Hand to face contact a key issue

Oliver J. Harding
bmj.com, 5 Oct 2009 [Full text]

International Journal of Clinical Skills Handwashing advice

Alison Anderson
bmj.com, 7 Oct 2009 [Full text]

Evidence for handwashing for the GPs

William CW Wong
bmj.com, 8 Oct 2009 [Full text]

Online poll

Find out more on doc2doc >>