A camp New York City Mixed Vacation said 31 campers aged 7 to 11 tested positive for Covid-19 - but none of their vaccinated campers aged 12 and older did. The camp Pontiac, located in Copake, NY, about a two-hour drive from New York City, said in a letter to parents the first positive test result was received on July 16. The virus then spread further. The initial outbreak was on the girls 'side, but the latest new cases are on the boys' side, Jack Mabb, director of the health department of the United States, said Thursday. Columbia County, in an email to CNN. Most cases are due to tests performed on symptomatic campers last weekend. Alls the positive cases, except a few, were discharged from the camp with 88 contacts, he said. The few who have not been sent home live too far away to get home easily, he said. Camp Pontiac has 550 campers on campus; about half are between 7 and 11 years old and half between 12 and 17 years old, according to Mabb.Read more Vaccinated children can go to summer camp without a mask, CDC says None of the campers 12 or older have tested positive for Covid-19, as all but four are vaccinated, he said. There are 275 employees at the camp and less than 10 are unvaccinated, he added. On the recommendation of the state health department, Camp Pontiac tests all campers unvaccinated at least twice this week.The outbreak illustrates the continued spread of Covid-19 even as it shows the importance of vaccinations, which studies have shown are safe and offer a protection against the disease and its most serious risks. Being fully vaccinated gives you a high degree of protection against iinfections, and an even higher degree of protection against serious illness, hospitalization, said U.S. Centers for Disease Control and Prevention director Dr. Rochelle Walensky on Thursday. These vaccines are among the most effective that we have in modern medicine. The CDC said the staff and campers who are fully vaccinated do not need to wear masks at camp . Children under 12 are not eligible to be vaccinated because manufacturers of vaccines are always test for efficacy and shooting safety for younger age groups . A timeline for their approval is unclear.