In cooperation with other institutions, the Freiburg Institute for Musicians’ Medicine, following the paper of May 6, 2020, has again revised the scientific findings and recommendations for making music and singing under COVID19 conditions (as of May 19, 2020).
The new recommendations provide more clarity and certainty on many points under which conditions and protective measures rehearsals and performances of orchestras, choirs and chamber music formations are currently possible. According to the current state of scientific research, individual questions can still not be answered conclusively. Nevertheless, it is now even better for orchestra employers, for organizers and for musicians to plan stage structures, rehearsal situations and processes so that the health of musicians and staff can be protected according to the current state of the art.
You can read the current recommendations here. Alternative link: https://www.mh-freiburg.de/hochschule/covid-19-corona/risikoeinschaetzung/. Original text is in German. Please, take Google translator or any other translation software to get an idea of the content.