A German study, conducted by the Hermann-Rietschel-Institu in Berlin, indicates that the risk of exposure to the virus is higher in schools and offices. Conversely, according to the study, the risk of infection is lower in movie theaters, theaters, or museums.

In Switzerland, contact tracing services face some difficulties and the vast majority of infections cannot be attributed to one place or another, company or another. A big limitation when it comes to enforcing the lockdown.

To classify the most dangerous or least dangerous places, Berlin researchers assessed the number of people who would likely transmit the virus if an infected person entered an environment, based on the time the infected person spends, the ventilation of the places, the type of activity, the profession of the buildings, and the protection measures adopted.

The study shows that for example theaters and museums have an occupancy rate of 30% and if everyone wears a mask, the risk of contagion is 0.5 (0.6 with the same conditions with 40% occupancy). Worker up to 1 in supermarket though masks. 1.1 and 2.3 with 25% and 50% occupancy respectively for restaurants. The German researchers also add that the risk of infection is 2.9 in high school, with mask wearing rising to 5.8 unprotected. The stakes are high even in offices with multiple people: at 50% of occupancy and without a mask, the factor is 8.0, rising to 11.5 in fully occupied schools where the mask is not worn (1.6 with 20% of admissions and all with masks). On public transport (with flights of at least 3 hours) and 50% seat occupancy with passengers wearing masks, the factor is 1.5.