High Rate of SARS-CoV-2 Transmission Due to Choir Practice in France at the Beginning of the COVID-19 Pandemic.
Nathalie Charlotte
PMID 33386191WHAT IT FOUND
A two-hour indoor choir rehearsal with no masks and poor ventilation led to 70% of the 27 attendees becoming ill.
The conductor and accompanist, who stood in front of the singers, had a 100% attack rate. Singing in close quarters spread the virus efficiently.
Key findings
01Seventy percent of the 27 participants at the March 12 rehearsal developed COVID-19 symptoms or tested positive, with the conductor and accompanist having a 100% attack rate.
02The rehearsal took place in a small, unventilated room with participants seated less than six feet apart and without masks.
03Thirteen tertiary cases were later reported, mostly among household contacts of the ill choir members.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study is a single case report, so it cannot establish general causality or apply to all choir settings. Most participants were not tested for SARS-CoV-2, relying on clinical diagnosis, which may have led to under- or over-ascertainment of cases. The index case(s) were not identified, making it difficult to pinpoint the exact source of the outbreak. Data were collected retrospectively via questionnaires and interviews, which may be subject to recall bias.
Declared interests
The president of the choir collected the questionnaires and was interviewed, which introduces potential bias in data collection and reporting. No other conflicts of interest are explicitly stated.
The easy way to misread this
Do not generalize these findings to all choir practices or assume that similar attack rates would occur in different settings. This is a single case report from early 2020, before widespread public health measures were implemented, and the lack of testing for most participants means the true extent of infection is uncertain.