Delaguerre 2022.

Methods	Prospective, open‐label, non‐inferiority randomised (2:1), controlled trial
Participants	Study included healthy individuals aged 18 to 45 years, with negative RADT test 3 days prior to concert event, with no risk factors and not living with someone with risk factors, and residing in Paris. Study excluded people with positive RADT test within 3 days before the gathering. People with clinical signs suggestive of an infectious respiratory disease, or with risk factor for severe COVID‐19, or living with someone with risk factors for severe COVID‐19. Persons not covered by French National Health Insurance or who cannot stand for the duration of the experiment (about 5 hours from entry line to exit) were excluded. Person under legal guardianship, pregnant woman or woman orally declaring non‐use of effective contraception and breastfeeding woman were also excluded.
Interventions	Participants were randomly assigned to: medical face mask wearing during an indoor concert event, or not attending.  Both groups had RADT test 3 days before the event  Saliva samples for RT‐PCR were collected from both groups on D0 and D7 using self‐saliva‐collection kits
Outcomes	Primary outcome: the number of SARS‐CoV‐2‐positive RT‐PCR tests on self‐collected saliva at day 7. Secondary outcomes:  the conversion rate of salivary carriage between the day 0 and day 7 visits;  the percentages of adequately masked (nose and mouth covered) faces over the total 4‐hour period gathering.
Notes	French Ministry of Health. ITT and PP analysis were used. Several imputation for missing data. It is not clear if participants had COVID‐19 in the past (in the table with baseline characteristics it is reported quote: “”declared Covid‐19 history”: what does it mean? Surgical masks were worn also by all attendees, regardless of study participation? What is the intervention? Combined screening test + surgical mask?