(1/4) Study of a #COVID19 cluster of at least 260 people at a children's camp. More children (who didn't have to wear masks) were infected than adults (masks required); attack rate: 45.4% vs. 33.0%. Of 136 cases with symptom data, 36 (26.5%) asymptomatic.
https://www.cdc.gov/mmwr/volumes/69/wr/mm6931e1.htm?s_cid=mm6931e1_w

(2/4) Unlike adults, children were not required to wear masks. Doors and windows were not opened to increase ventilation. Cabins were shared by many people. Singing was a regular activity. These factors likely contributed to the high overall attack rate (44%).

(3/4) Limitations of the study include not all persons being tested, and test results were also not reported for some, which likely means attack rates were underestimated. Some cases may also have been infected prior to arriving at the camp, or shortly after.

(4/4) The authors wrote that the study "adds to the body of evidence demonstrating that children of all ages are susceptible to SARS-CoV-2 infection and, contrary to early reports, might play an important role in transmission."