https://freerepublic.com/focus/chat/3907739/posts?page=360#360
The study population “From May 12 to July 15, 2020, a total of 1848 of 3143 eligible recruits (58.8%) across nine recruit classes were enrolled in the CHARM study”.
Not surprised that negative controls were from July 2019. To be sure of negative, and to match the season.