How could COVID-19 spread when people sing together?

Droplets and Aerosols generated by singing & the risk of COVID-19 for choirs

A study led by Professor Raina MacIntyre raises questions about the risks of infection for people singing in groups, especially in poorly ventilated rooms.

The researchers took high-speed video of a person singing a major scale and then tracked the emissions of droplets and aerosols. They found certain notes, such as "do" and "fa", generated more aerosols than others - and they also found the direction of emissions changed with different consonants.

In their The Conversation article explaining the results, they say: "One of the assumptions in infection control guidelines is that respiratory droplets settle rapidly within one to two metres of the person emitting them. However, our results reveal most droplets we observed appeared not to settle rapidly, and tended to follow the ambient airflow. Therefore, without adequate ventilation, these droplets may persist in aerosol clouds. These observations may partially explain the higher infection rates of COVID-19 during group singing, even when people singing appear well."