Two hand sanitizers were compared in a Japanese household trial
In Japan, 568 participants from 417 households used one of two hand sanitizers for 72 days. The primary fever-plus-symptom outcome occurred in 12.3% with a new formulation versus 20.5% with a higher-ethanol comparator. Symptoms came from diaries, without tests identifying the viruses involved. The manufacturer funded the retrospectively registered trial; its result does not establish protection against every infection.
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Households were assigned to one of two products
The trial randomly assigned 417 households comprising Kao employees and family members to two products. The analysis included 568 people: 285 using a new formulation and 283 using the comparator. The two formulations differed: the new one had 62% ethanol and 0.05% benzalkonium chloride, whereas the other had 79.7% ethanol. Each participant was asked to use half a millilitre five to ten times daily over 72 days. This design compared specific products and quantities, rather than all methods of hand hygiene.[1]
Reported symptoms differed between groups
A counted event required a temperature of at least 37.8 degrees and one of three symptoms: coughing, throat soreness or a runny nose. It appeared in 35 users of the new product versus 58 users of the comparator, corresponding to 12.3% and 20.5%. The study estimated a hazard ratio of 0.58 for the timing of that outcome. Work restrictions were also reported less often in the new-product group. Participant diaries recorded symptoms; laboratory tests did not identify which, if any, viruses caused them.[1]
The trial does not settle every use condition
Kao funded the research and employed its authors. No group used ordinary care without a study sanitizer, so the products were not compared with every alternative. Half a millilitre per use does not establish performance at larger volumes or in other settings. The researchers registered the trial only after follow-up was complete. Independent, prospectively registered replication would strengthen the finding. The measured difference concerns one reported symptom definition, not proven protection from every respiratory infection.[1]
