Did singing together spread coronavirus to four choirs?
On 8 March this year, the Amsterdam Mixed Choir gave a performance of Bach’s St John Passion in the city’s Concertgebouw auditorium. It was one of the last major classical concerts to be held in the Netherlands before the country went into Covid-19 lockdown.
The performance had unexpected consequences. Days later, singers began to sicken, one by one, until 102 of 130 choristers had fallen ill with Covid-19. One 78-year-old died, as did three partners of choir members; singers ended up in intensive care; and conductor Paul Valk displayed serious symptoms.
Nor was this the only major chorus to suffer from Covid-19. Members of the Skagit Valley Chorale, based in Washington State, met for a rehearsal in March and within three weeks, 45 of them had been diagnosed with the disease or had symptoms. Three were hospitalised and two died. Similarly 50 members of the Berlin Cathedral Choir contracted the coronavirus after a March rehearsal, and in England many members of the Voices of Yorkshire choir became infected with a Covid-like disease earlier this year.
These alarming developments raise a critical question. Does public singing – not just in choirs, but at football matches or at birthday parties – help transmit the coronavirus that is the cause of Covid-19? Jamie Lloyd-Smith, an infectious diseases researcher at University College Los Angeles, said it was possible that an infected singer might disperse viral particles further than other infected individuals. “One could imagine that really trying to project your voice would also project more droplets and aerosols,” he told the Los Angeles Times. In this way, the virus would cause increased numbers of infections.
The idea is alarming. A traditional pastime imbued with widespread cultural importance appears to be posing a distinct threat to the health of singers, concert-goers, football fans and a host of others.
But not all scientists agree with the idea that our musical appetites pose a health. In particular, fluid mechanics expert Professor Christian Kähler of the Military University, Munich was highly doubtful about the dangers posed by concerts and decided to conduct experiments in the wake of the Amsterdam outbreak to find out how far singers and musicians expel air and droplets.
“I have been studying how droplets and aerosols behave for decades and I was very doubtful that musicians and singers were spreading the virus. So I decided to measure just how strong was the airflow from them,” Kahler told the Observer last week. “We studied singing in low and high frequencies and all sorts of things like that. We also studied different instruments. And based on the flow analysis we did of these performances we could clearly see what was going on.”
And yes, one or two instruments did pose threats in terms of their powerful air flow and might spread virus particles dangerously if some form of protection was not added. In particular the flute is especially strong while the oboe and clarinet also posed problems.
“The large wind instruments like the horn were not dangerous but the flute could be, it turned out. Its air flow is considerable.
“However, we also found out that singing is quite safe. It was not the cause of the outbreaks of Covid-19 at these concerts ,” he said. “Air was only propelled about half a metre in front of a singer, and that is not far enough to cause the infection levels of these outbreaks.”
Kähler said the virus was probably spread among chorus members because of their close proximity to each other before and after rehearsals and performances. As he pointed out: “These outbreaks among choir members all occurred during the early days of the Covid-19 pandemic, before lockdowns were imposed and before our minds were concentrated on the importance of social distancing. Choir members probably greeted each other with hugs, and shared drinks during breaks and talked closely with each other. That social behaviour was the real cause of these outbreaks, I believe.”
This point was also stressed by Professor Adam Finn of Bristol University. “The evidence for a link with singing and spreading the virus may look compelling but is still anecdotal,” he said. “Without data from comparably large groups who interacted in the same way but didn’t sing, it’s hard to be certain that the singing was responsible.
“The point is that we now live in a world where the constant need for risk evaluation is suddenly noticeable. Before, we did it all the time without thinking about it.”