For Germany: https://www.corona-in-zahlen.de/weltweit/deutschland/
For Heidelberg: https://www.corona-in-zahlen.de/landkreise/sk%20heidelberg/
Wearing a mask (FFP2 or medical mask) is mandatory in all public places including in public transportation
Keep the distance - minimum 1,5 meters
Disinfect your hands
Ventilate rooms regularly
Complete the questionnaire for visitors
https://www.auswaertiges-amt.de/en/coronavirus/2317268