Large sporting event in US linked to 649 cases of COVID-19
Simon Collins, HIV i-Base
The US public health response to tracing cases of COVID-19 linked to a motorcycle rally identified 463 PCR-confirmed primary cases and 186 secondary and tertiary infections.
The rally was held in August 2020 and attended by more than 460,000 people. It included both indoor and outdoor activities, but with little use of masks and physical distancing.
This paper is notable for reporting the approach to tracking outcomes from a single event that then spread widely across the US.
The same issue of CID that carried this report, included a second transmission paper on COVID-19 at several construction sites in New York. 
This is useful for issues of occupational exposure in environments that include limited ventilation during some activities, close proximity of coworkers and the importance of addressing this risks as lock down is relaxed.
- Carter RJ et al. Widespread SARS-CoV-2 transmission among attendees at a large motorcycle rally and their contacts, 30 US jurisdictions, August–September, 2020. Clinical Infectious Diseases, ciab321, doi:10.1093/cid/ciab321. (29 April 2021).
Bushman D et al. COVID-19 Outbreaks at Two Construction Sites — New York City, October–November 2020. Clinical Infectious Diseases, ciab312, doi:10.1093/cid/ciab312. (29 April 2021).