Rapid-Cycle Re-Implementation of TRAining Facilities in Norway

This study tests the randomized re-opening of training facilities in Norway in relation to the COVID-19 pandemic. The investigators will use the recently developed concept of rapid-cycle randomized implementation to assure fast and safe re-introduction of training facilities by randomized testing of access restriction and measure virus exposure and immunity as well as clinical disease during the intervention to enable safe and timely downgrading of COVID-19 restrictions. Members of training facilities in Norway age 18 to 64 years without COVID-19 related comorbidity will after informed consent be randomised to either access to training or no access in a first 2-week cycle. Testing for COVID-19 and ascertainment of clinical disease will be performed after the first cycle. If there is no clinically meaningful difference between the arms, new cycles may be implemented subsequently, e.g. with less distancing restrictions or wider age groups.