Online classes are the only truly safe way to avoid COVID-19 virus contamination. The experience of the previous months also shows that online lessons really do work efficiently, even (occasionally) with minimal resources.
Live contact lessons always come with a heightened risk of infection with the COVID-19 virus, both for student and teacher and their respective families. That is why they’re always accompanied by strict security measures. However, they are sometimes desirable, and in the case of playing in ensemble really necessary.