To inform about behavioural gender and age differences in compliance with hand hygiene recommendations during the COVID-19 pandemic in Switzerland.

Observational study (24–25 June and 1–3 July 2020); validation study (4 December 2020); gender and age group estimated by observers.

Observations occurred in five supermarkets.

All customers entering the supermarkets during a 3-hour period per day (n=8245 main study) and during 1 day (n=1918 validation study).

We observed whether people disinfected their hands.

The study reveals considerable differences with respect to gender and age: For women, 58.7% (95% CI 57.3 to 60.0%) were disinfecting their hands vs 50.4% (95% CI 48.6 to 52.2%) of men. With respect to age, we identified a steep increase across age groups up to the age of 60 years and older with 35.5% (95% CI 30.7 to 40.5%) of youth (12-17 yrs) disinfecting their hands, 50.5% (95% CI 49.1 to 51.9%) of adults (18-59 yrs) vs 69.0% (95% CI 67.1 to 70.9%) of the golden age group (60-74 yrs) and 67.2% (95% CI 61.1 to 72.9%) of people older than 75 years. The validation study confirmed these differences.

The study documents substantial differences in hand hygiene compliance between gender and age groups. This should be considered in the design of protective measures to ensure clean and safe hands.