September 16, 2010 (Boston, Massachusetts) — Despite expectations to the contrary, the use of a hand disinfectant did not achieve significant protection against transmission of rhinovirus-associated illness, influenza-associated illness, or infections in a randomized double-blind trial presented here at the 50th Interscience Conference on Antimicrobial Agents and Chemotherapy. Hand disinfectant did reduce the incidence of the common cold, however.
"These results suggest that hand-to-hand transmission is not as important as we assumed for flu, and we may need to reconsider that conclusion. I've been writing for 20 years that rhinovirus is transmitted hand-to-hand, so I am very surprised by these results," said Ronald Turner, MD, lead author of the study. Dr. Turner is professor of pediatrics at the University of Virginia in Charlottesville.
The investigators enrolled 212 volunteers and randomized them to the use of hand lotion containing 2% citric acid and 2% malic acid in 70% ethanol or to no treatment for 10 weeks, Turner said. The hand lotion was used every 3 hours or after hand washing.
Dr. Turner pointed out that hand lotion has both immediate and persistent activity against rhinovirus and influenza on the hands, according to several studies. It is frequently recommended for reducing transmission of rhinovirus- and influenza-associated illnesses.
Both groups kept daily diaries of symptoms and underwent a nasal lavage for polymerase chain reaction once a week during the fall flu season and 2 lavages for each common cold they experienced.
In an intent-to-treat (ITT) analysis that comprised all patients, the incidence of common cold was significantly reduced in the treated group (39% vs 58%; P = .01). In a per-protocol analysis (only compliant patients), 43% of the treated subjects had at least 1 illness, compared with 58% of the untreated subjects (P = .06).
For rhinovirus infection and for rhinovirus-associated illness, no significant difference was seen between the 2 groups in either the ITT or per-protocol analyses. For influenza infection and influenza-related illness, results were also similar for the 2 groups for both analyses.
Study Results Unexpected
The results of this study are somewhat surprising, agreed David Weber, MD, professor of medicine, pediatrics, and epidemiology at the University of North Carolina in Chapel Hill.
Dr. Weber pointed out that the study was not designed prospectively to compare hand-to-hand transmission with another transmission route.
"We know from older studies that hand-to-hand transmission is possible for flu and rhinovirus. Alcohol products should kill 99% of the influenza virus on hands," he said.
"In this study, we can't tell what percentage of influenza and rhinovirus illness was due to hand-to-hand transmission and what percentage was due to transmission by nasal droplet [or other routes]," he said.
The study was sponsored by Dial Hand Cleanser, a subsidiary of Henkel Products. Dr. Turner reports receiving support from Henkel Products. Dr. Weber reports receiving support from Policy Analysis Inc and Forest Research Institute.
50th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC): Abstract V-444. Presented September 12, 2010.
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