The last year has seen the biggest boom of measles, both domestically and globally, in decades. The United States, alone, has seen a record year of measles cases, with nearly 900 cases confirmed thus far by the CDC.

And with the summer upon us, precautions are already being taken to try and stem the spread of the virus further.

Summer camps are one such space that will be taking a stricter stance when it comes to vaccinations. According to NBC News, some camps are preparing to turn away unvaccinated children to avoid possible measles outbreaks.

Many schools have taken similar stances regarding vaccinations, turning away kids who were and being sued because of it.

“I used to accept kids if they had a religious exemption, but now I'm not,” Rosmarin’s Day Camp operator Scott Rosmarin said. Rosmarin said he has already sent out a letter to parents whose kids previously attended, explaining that they will turn away parents who cite religious or philosophical reasons for their kids being unvaccinated. He continued, “If I lose a couple kids, I lose a couple kids ... You've got to do what's right.”

Rosmarin, in particular, has extra cause to be concerned because his camp is located in the Hudson Valley, New York. New York State has contributed to most to the measles outbreaks, mainly in Brooklyn and Rockland County.

And other camps across the country have been seeking advice from their state’s health departments on how to handle the situation. The Association of Camp Nursing posted a letter on its website recommending that all campers should be properly immunized before camps open up. The letter also states that the only exemptions that are acceptable are medical.

Measles vaccine A medical worker holds a measles-rubella (MR) vaccine at a health station in Banda Aceh in Aceh province on Sept. 19, 2018. Photo: CHAIDEER MAHYUDDIN/AFP/Getty Images