This shot of the Death Chorus is based on the incident at the start of the pandemic when a church chorus held a rehearsal. They thought they were doing the right things by not hugging and avoiding hand shakes. They didn’t however wear n-95 masks. At the time people were being discouraged from buying masks because health care workers needed them more and there was some worry that supplies might run out.
The two guys in hazmat suits are animated walking forward for a step. They were reworked to keep them high resolution.
I don’t think any other animation is needed. I could open the skeletal jaws to make it look like they are singing but the shot is so short I don’t think such subtle animation would be noticed. Scenes like this don’t seem to fly in America, but Germans seem to love macabre scenes like this.