Two randomized controlled trials of virucidal nasal tissues in the prevention of natural upper respiratory infections.

Two six-month randomized, controlled double-blind trials of the efficacy of virucidal nasal tissues in the prevention of natural colds were conducted in Charlottesville, Virginia, between 1983 and 1986. Tissues impregnated with malic and citric acids and sodium lauryl sulfate were used in both trials. Placebo tissues contained saccharin in the first trial and a mixture including succinic acid in the second. A total of 186 families were evaluable after completion of trial I, and 98 families were evaluable in trial II. The antiviral tissues were associated with 14 and 5% relative reductions in the overall rate of colds in the first and second trials, respectively. In the first study, this appeared to be due to an appropriate fall in secondary illnesses with a relative reduction in the ratio of secondary to primary illnesses of 32%. In trial II, however, the small and statistically insignificant reduction was primarily due to a drop in the rate of primary illness (which cannot be attributed to tissue efficacy), and the ratio of secondary to primary illness was actually 5% higher in the group with active tissues than in the placebo group. We conclude that when rigorously used in a study protocol, virucidal tissues may offer a modest reduction of secondary colds in the home, but for reasons currently unknown, do not have a major effect on the overall rate of colds.