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

Jefferson, Tom, Del Mar, Chris, Dooley, Liz, Ferroni, Eliana, Al-Ansary, Lubna A., Bawazeer, Ghada A., van Driel, Mieke L., Foxlee, Ruth and Rivetti, Alessandro (2009) Physical interventions to interrupt or reduce the spread of respiratory viruses: systematic review. British Medical Journal, 339 7724: b3675.1-b3675.10. doi:10.1136/bmj.b3675

Author Jefferson, Tom
Del Mar, Chris
Dooley, Liz
Ferroni, Eliana
Al-Ansary, Lubna A.
Bawazeer, Ghada A.
van Driel, Mieke L.
Foxlee, Ruth
Rivetti, Alessandro
Title Physical interventions to interrupt or reduce the spread of respiratory viruses: systematic review
Journal name British Medical Journal
ISSN 0959-8146
Publication date 2009-09-01
Sub-type Article (original research)
DOI 10.1136/bmj.b3675
Open Access Status Not Open Access
Volume 339
Issue 7724
Start page b3675.1
End page b3675.10
Total pages 10
Place of publication London, United Kingdom
Publisher BMJ Group
Language eng
Formatted abstract
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.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Discipline of General Practice Publications
School of Medicine Publications
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Citation counts: TR Web of Science Citation Count  Cited 74 times in Thomson Reuters Web of Science Article | Citations
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