A health report into one of the first US Covid-19 outbreaks among a church choir in Washington effectively put the stoppers on community choir practices the world over.
Fifty-three people who went that night developed symptoms and the local health department concluded that one person who later tested positive — and who had shown signs of a cold beforehand — was most likely the single source.
Hundreds of scientific papers quoted the investigation, claiming that March 2020 Skagit Valley Chorale rehearsal in Mount Vernon, Washington Presbyterian Church one of the pandemic’s first so-called super-spreader events.
Now a re-examination of the data by Brunel University London, Nottingham Trent University and Brighton and Sussex Medical School, which looked at the epidemiological curve, reveals the early investigation was probably wrong. It now appears that – in the majority of cases – infection occurred two to four days before the practice, showing Covid was already rife in the community.
‘We show it is vanishingly unlikely that this was a single point source outbreak as widely claimed and on which modelling has been based,’ says their study published in the journal, Public Health.
‘An unexamined assumption has led to erroneous policy conclusions about the risks of singing, and indoor spaces more generally, and the benefits of increased levels of ventilation,’ the team adds.
In the UK alone, where there’s at least 40,000 choirs, 2.14 million people sing regularly, according to figures from Voices Now, which lists the health benefits of community singing. Britain banned indoor singing in March 2020 and it was 18 months before the prohibition was finally relaxed.
TV choirmaster Gareth Malone, from BAFTA-winning reality series The Choir, said: “The outbreak in the Skagit Valley Chorale sent shockwaves round the singing world. I’m sure singers everywhere will welcome the fact that this is being looked at again. Singing with others is so good for us in so many ways, but some people are still fearful about singing because of Covid, and so it’s important that we are constantly re-evaluating the evidence.”
“The Skagit County story is a good example of a familiar problem, where an early provisional, study gets taken for granted and cited without critical re-evaluation,” said Professor Robert Dingwall of Nottingham Trent University. “There are likely to be many similar cases out there,” he warns “and the scientific community needs to find better ways of detecting them, if policy mistakes are to be avoided.”
While the US investigation never named anyone, ‘one individual bears the moral burden’, the fresh study highlights. Led by public health infectious diseases specialist Professor Jackie Cassell from Brighton and Sussex Medical School, the team now call for the original claims to be re-examined and for more ethical responsibility in mentioning a point source in outbreak investigations.
“Ethically we think the original outbreak investigation should not mentioned an index case,” explained Brunel University London’s Dr Colin Axon. “That’s because everybody in that choir would know who the first person was. So mentioning it puts that person at risk, effectively saying they’re responsible for the death of their friends. That’s a massive and unacceptable moral burden.”
The public health department’s early findings, and the fear they generated, had a huge influence on UK Government policy around singing, explained Music Director and Conductor, Sam Evans. “In May 2021, the Government planned to release many Covid restrictions as part of the ‘road map’. But singing was placed under continued restriction, because of a widespread belief at the highest levels that it presented a unique risk.
“This re-evaluation of the Skagit Valley Chorale outbreak shows that fear was unfounded.”
