In a new study published this month in the British Medical Journal, researchers sought to review the evidence of effectiveness of physical interventions to interrupt or reduce the spread of respiratory viruses.
The researchers culled data from a number of sources for their literature review, including the Cochrane Library, Medline, OldMedline, Embase, and CINAHL, and looked at studies of any intervention to prevent the transmission of respiratory viruses (isolation, quarantine, social distancing, barriers, personal protection and hygiene).
The researchers looked at 59 studies; 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 researchers found that the highest quality cluster randomized trials suggested that spread of respiratory viruses can be prevented by hygienic measures in younger children and within households. They also found that evidence that N95 masks were superior to simple surgical masks was limited, and that the incremental effect of adding virucidals or antiseptics to normal handwashing to reduce respiratory disease remains uncertain. They discovered limited evidence of the effectiveness of social distancing.
The researchers concluded that 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. They say that additional resources should be invested into studying which physical interventions are the most effective, flexible and cost-effective means of minimizing the impact of acute respiratory tract infections.
To access this review,
Reference: Jefferson T, et al. Physical interventions to interrupt or reduce the spread of respiratory viruses: systematic review. BMJ 2009;339:b3675
