Well considering the age of this choir this was a really stupid move, how many times to you have to repeat to people that the elderly are a very high risk!! Washington was the epicenter for some time and this was extremely STUPID!!!
The 50% asymptotic theory is also disproven with this older group where 75% (45/60) showed symptoms, although the small size could be an otherwise explainable result. It would be extremely useful for the other 15 to get tested to see if they are carriers or asymptotic. With singer spray and deep breaths, if the transmission were airborne, youd think ALL were similarly exposed.