(CNN) More than 80 teens and adult staffers from a Central Illinois summer camp tested positive for Covid-19 in an outbreak that has impacted people across three states, officials said.
The Crossing Camp in Schuyler County held in mid-June did not check vaccination status for campers or staffers, and masks were not required indoors at the camp, the Illinois Department of Public Health (IDPH) said in a news release.
The Crossing Camp has not responded to calls, email or Facebook messages left by CNN on Monday and Tuesday.
All campers and staff were eligible for vaccination, although "IDPH is aware of only a handful of campers and staff receiving the vaccine," the department said Monday.
One unvaccinated young adult who tested positive after attending the camp was also hospitalized, according to IDPH.
In Illinois, 46.1% of the population is fully vaccinated, according to the latest data. However, officials across the country have are becoming alarmed by the reluctance of young adults to get vaccinated, especially as the more transmissible Delta variant is spreading more widely.
"The perceived risk to children may seem small, but even a mild case of COVID-19 can cause long-term health issues," IDPH Director Dr. Ngozi Ezike said in Monday's statement. "Additionally, infected youth who may not experience severe illness can still spread the virus to others, including those who are too young to be vaccinated or those who don't build the strong expected immune response to the vaccine," she said.
IDPH said that at least two individuals from the camp also attended a nearby conference, which resulted in 11 additional positive cases of Covid-19.
The week-long camp from June 13-17 was designed was for 8th graders -- through graduating seniors.
An upcoming camp created for fourth- and fifth-grade students has been postponed to August due to the outbreak, according to a message posted on its official website.
" We were so looking forward to spending time with your campers this weekend, but we believe the best way to value and love our students, difference makers, and staff is to delay camp until a safer time," it read.
The Schuyler County Health Department worked with camp staffers "to provide guidance and mitigate the situation," according to a county statement from last week. The Crossing Camp also followed CDC guidelines in relation to the "cleaning and disinfection of their facility," the Schuyler County Health Department said.
County and state health officials are advising anyone who visited the camp during the mid-June timeframe to get a PCR test, even if they are not experiencing Covid-19 symptoms.