Although many have touted strategies from travel avoidance to Tamiflu to halt the spread of H1N1 flu or swine flu, a large body of evidence from the Cochrane Library suggests that concentrating on children's hygiene might be the best way to reduce the spread of respiratory illnesses.
"The evidence in children is clear. Hand washing offers protection against a lot of things, not just respiratory viruses," said lead review author Tom Jefferson, M.D.
Although the Centers for Disease Control and Prevention cannot say how H1N1 flu spreads definitively, the CDC suggests that like the seasonal flu, the H1N1 flu spreads from person to person through sneezing and coughing.
Led by Jefferson, a medical epidemiologist at the Vaccines Field of the Cochrane Collaboration in Rome, researchers identified 51 studies examining a variety of interventions to contain respiratory virus epidemics, including influenza.
The updated review appears in the latest issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates medical research. Systematic reviews like this one draw evidence-based conclusions about medical practice after considering both the content and quality of existing medical trials on a topic.
Frequent hand washing, using gloves, gowns and masks with filtration, and isolating people believed to be sick effectively reduced transmission of viral respiratory diseases, the authors found. The greatest potential for preventing disease spread was not among adults, though.
Children "are the least hygienic beings among us, but they are also the most social beings. Acting on children is probably the best, most effective intervention," Jefferson said.
One large study in the review, conducted in 2005, examined rates of respiratory disease among 4,332 children in poor Pakistani households. Children who washed their hands several times daily with plain or antibacterial soap experienced 50 percent fewer episodes of respiratory illness, such as pneumonia or cough, compared to children with standard hygiene practices.
Other studies showed that younger children who received hand-washing instruction at school or home experienced significant decreases in respiratory illness. One study also found that school absenteeism dropped 43 percent when children used alcohol gels in conjunction with hand washing.
"It's not surprising and [it is] useful to identify that children could be a source. Transmission occurring among children frequently can be the source of transmission to older people," said Yvonne Maldonado, M.D., chief of the division of pediatric infectious diseases at the Stanford University School of Medicine.
"In terms of the H1N1 situation, I think a lot of their findings are applicable," she said.
The review also examined evidence from a small study, involving only six volunteers, suggesting paper surgical masks may not be as effective a barrier to flu virus as the thicker N95 mask. Even when participants wore up to five layers of paper surgical masks, they were not able to prevent the spread of infected droplets as well as N95 facemasks. N95 facemasks are a type of respirator designed to block 95 percent of very small airborne particles, but they are expensive, hot, uncomfortable, and unable to be worn by children.
When it comes to facemasks, "It's always been a tradeoff between performance and protection. The longer you wear them, the hotter you get and the more difficult it is to concentrate. Based on a small study done to examine experimental effects in lab, wearing them protects," against virus, Jefferson said, but added that masks are impractical for use over long time periods.
"There is some controversy about whether or not N95 facemasks solve the problem, but there's not one thing that will solve all the problems. We do know that if anything, these kinds of barriers keep people isolated and may reduce contamination," Maldonado said.
"While there are not a lot of data to support certain interventions, there are not data to support that they shouldn't be used either," Maldonado said.
What about antiviral influenza drugs, such as Tamiflu?
Jefferson, who recently updated a 2009 Cochrane review on antiviral influenza drugs, commented that these drugs "don't prevent influenza, but prevent symptoms if taken [as a precaution]. They appear to interrupt transmission in families and shorten the duration of illness just over a day provided they're taken within 48 hours of symptoms appearing," Jefferson said.
"But they cost a lot of money, they are a logistical problem, there are reports of increasing resistance, and they have been linked with, albeit rare, psychotic episodes in adolescents," Jefferson said.
In contrast, hand-washing, covering your mouth and nose if you sneeze, and staying at home if you're sick are inexpensive, easy-to-implement strategies to prevent infection's spread, the authors say.
Maldonado also suggested that parents work together with teachers and daycare providers to encourage regular hand washing in children to reduce respiratory disease transmission.
The UK's National Health Service provided support for the research.
The Swine Flu Task Force of the Cochrane Library has slide shows and podcasts available at http://cochrane.org/news/articles/influenza_2009.html
Jefferson T, Foxlee R, et al. Interventions for the interruption or reduction of the spread of respiratory viruses. The Cochrane Database of Systematic Reviews 2009, Issue 2.
Jefferson T, Demicheli V, et al. Neuraminidase inhibitors for preventing and treating influenza in healthy adults. The Cochrane Database of Systematic Reviews 2009, Issue 2.