Research by UK universities has found that a health report into an early US Covid-19 outbreak among a church choir, which effectively halted community choir practices worldwide, was based on flawed data.
Fifty-three people who attended the March 2020 Skagit Valley Chorale rehearsal in Mount Vernon, Washington state, developed Covid symptoms. 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, and labelled the choir rehearsal one of the pandemic’s very first 'super-spreader' events.
Now, however, a team from Brunel University London, Nottingham Trent University and Brighton and Sussex Medical School has re-examined the data, looking at the epidemiological curve – and has concluded that the earlier investigation was probably wrong. Instead, it now seems likely that, in most cases, infection had already occurred two to four days before the choir rehearsal, and that Covid was already rife in the community.
‘We show that it is vanishingly unlikely that this was a single point source outbreak as widely claimed and on which modelling has been based,’ says the study, which is 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.'
There are some 40,000 choirs in the UK, with 2.14 million people singing regularly, according to figures from Voices Now, which also lists the health benefits of community singing. Indoor singing was banned here at the start of the pandemic, in March 2020: choirs were not allowed to come together again for a further 18 months.
TV choirmaster Gareth Malone, from the 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.'
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'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, and the scientific community needs to find better ways of detecting them, if policy mistakes are to be avoided.'
Early findings by the public health department had a major influence on UK Government policy around singing during the early stages of the pandemic. 'In May 2021, the Government planned to release many Covid restrictions as part of the ‘road map’,' notes choral conductor Sam Evans. '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.'