Were choirs ever Covid hotspots?

By | 14th December 2022

One of the first Covid outbreak reports was produced by the public health department for Skagit County in Washington State, USA. It is a professional piece of work that describes the infection of 53 members of a choir who attended a rehearsal in March 2020. Two of the victims died. The investigators speculate about the possible means of transmission and about the likelihood of a single source for the infection. Later readers turned these hypotheses into ‘findings’ and used the report to argue that choral singing was a high risk activity that should be subject to exceptional degrees of control at the height of the Covid pandemic and beyond.

Professor Jackie Cassell, a respected infectious disease and public health specialist, was approached by Sam Evans, a professional music director, to review the evidence from this outbreak, which had been so influential. She recruited Dr Colin Axon, a physicist, and myself, as collaborators. Our reanalysis, partly guided by later evidence on incubation periods, air flow and viral decay, showed that it was highly unlikely that everyone had been infected by a single person. There must have been several people who had been infected elsewhere. Many previous users of the original report had overlooked its tentative character. The authors’ proposed interpretations should have been revisited as additional evidence was published.

It is impossible to say that no-one was infected at the event but the risk was clearly not exceptional compared with other indoor spaces and activities.

Read our paper in the, peer-reviewed, journal Public Health at https://doi.org/10.1016/j.puhe.2022.11.007

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