High Rate of SARS-CoV-2 Transmission due to Choir Practice in France at the Beginning of the COVID-19 Pandemic

Background: There has been very little focus on the individual risk of acquiring COVID-19 related to choir practice. Methods: We report the case of a high transmission rate of SARS-CoV-2 linked to an indoor choir rehearsal in France in March 2020 at the beginning of the COVID-19 pandemic. Results: A total of 27 participants, including 25 male singers, a conductor and an accompanist attended a choir practice on March 12, 2020. The practice was indoor and took place in a non-ventilated space of 45 m2. The mean age of the participants was 66.9 (range 35-86) years. 70% of the participants (19 of 27) were diagnosed with COVID-19 from 1 to 12 days after the rehearsal with a median of 5.1 days. 36% of the cases needed a hospitalization (7/19), and 21% (4/19) were admitted to an ICU. The index cases were possibly multiple. Discussion: The choir practice was planned in March 2020 at a period when the number of new cases of COVID-19 began to grow exponentially in France because SARS-CoV-2 was actively circulating. The secondary rate attack (70%) was much higher than it is described within households (10-20%) and among close contacts made outside households (0-5%). Singing might have contributed to enhance SARS-CoV-2 person-to-person transmission through emission of droplets and aerosolization in a closed non ventilated space with a relative high number of individuals. Conclusions: Indoor choir practice should be suspended during SARS-CoV-2 outbreaks. Further studies are necessary to test the spread of the virus by the act of singing. As the benefits of the barrier measures and social distancing are known to be effective in terms of a reduction in the incidence of the COVID-19, experts recommendations concerning the resuming of choir practice are necessary.