A few hundred children came down with Covid-19 at a summer camp in Georgia in the United States, health authorities said on July 31.
The virus infected at least 260 of the 597 attendees, the Centers for Disease Control and Prevention said.
However, the true number was likely higher since test results were only available for 58 per cent of the group.
These new cases has shown that minors are both susceptible to infection and are carriers of the disease for transmission.
No masks required for participants
The camp had ignored the CDC's advice for all participants in summer camps to wear cloth masks.
The camp required masks for staff only.
But it adhered to a state executive order requiring all participants to show proof of a negative Covid-19 test taken 12 days or less before their arrival.
Other precautionary measures included physical distancing, frequent disinfection of surfaces, keeping children among the same small group, and staggering the use of communal spaces.
Hundreds of youths exposed
The camp held an orientation for 138 trainees and 120 staff members from June 17 to 20.
Many of the staff members were aged 21 and younger.
The trainees left but staff remained when the camp officially opened on June 21.
A total of 363 campers, who ranged in age from six to 19, joined the camp, as well as three more senior staff members.
What activities they did
Camp attendees slept in cabins housing up to 26 people.
They "engaged in a variety of indoor and outdoor activities, including daily vigorous singing and cheering," the report said.
One person felt unwell
On June 23, a teenage staff member left camp after developing chills the previous evening.
The staff member was tested for the novel coronavirus on June 24 and got a positive result the same day.
The camp began sending campers home that day.
The camp was closed on June 27.
A health investigation started on June 25 found that 260 of 344 people for whom test results were available were positive.
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