(Research: Physical interventions to interrupt or reduce the spread of respiratory viruses: systematic review) http://www.bmj.com/cgi/doi/10.
Hygiene and physical measures, such as handwashing, wearing masks and isolating potentially infected patients, are highly effective in preventing the spread of viral infections (including influenza) and should be given higher priority in national pandemic preparation plans, argue researchers in a study published on bmj.com today.
In 2007, Professor Tom Jefferson and colleagues showed that physical interventions, such as handwashing and wearing masks, gloves and gowns are highly effective in preventing the spread of respiratory viruses. However, the current mainstay of pandemic interventions still seems to rest on vaccines and antiviral drugs with little evidence supporting their widespread use, especially against a seemingly mild threat like the new H1N1 (swine flu) virus.
So the team set out to update their 2007 review by analysing the results of 59 published studies on the effectiveness of physical measures to interrupt or reduce the spread of respiratory viruses such as influenza and SARS.
They included any intervention to prevent viral animal-to-human or human-to-human transmission of respiratory viruses (isolation, quarantine, social distancing, barriers, personal protection and hygiene) compared with do-nothing or with another intervention. They excluded vaccines and antiviral drugs.
Differences in study design and quality were taken into account to minimise bias.
The results show that regular handwashing (more than 10 times a day) and wearing masks, gloves and gowns were effective individually against all forms of acute infectious respiratory disease, and were even more effective when combined (only three patients would need to be treated in this way to prevent one case of respiratory disease).
The highest quality trials suggested that spread of respiratory viruses can best be prevented by hygienic measures in younger children and within households.
The team found limited evidence that the more uncomfortable and expensive N95 masks were superior to simple surgical masks and they can also cause skin irritation. However, the effect of adding antiseptics to normal handwashing to reduce respiratory disease remains uncertain.
Global measures, such as screening at entry ports were not properly evaluated, and there was limited evidence that social distancing was effective.
Many simple and low cost measures can be highly effective at reducing transmission of epidemic respiratory viruses, especially when they are part of a structured programme including education, and when they are delivered together, say the authors.
They call for nationwide handwashing programmes and personal hygiene teaching in schools.
In situations of high risk of transmission, barrier measures such as gloves, gowns, and masks with filtration apparatus and isolation of likely cases should also be implemented.
Society should invest more resources into studying which physical interventions are the most effective, ways to facilitate their introduction, and flexible and cost-effective means of minimising the impact of acute respiratory infections, they conclude.
Dr Tom Jefferson, Cochrane Acute Respiratory Infections Group, Roma, Italy