Just before the Winter Olympic Games are set to begin in PyeongChang, South Korea, a norovirus outbreak has struck the area, with 86 cases confirmed so far.

The Korean Centre for Disease Control and Prevention confirmed the number on Wednesday, after previously reporting 32 cases on Tuesday.

“The peak season for norovirus is January and February, so unfortunately we’re in a bad time of year where outbreaks occur,” said Kim Hyunjun, the center’s director.

Though no athletes have been confirmed sick so far, the majority of cases are coming from Odaesan Youth Centre, which is housing about 1,200 security personnel who have now been quarantined for showing norovirus symptoms. Twelve police officers have been confirmed sick, as well as three kitchen staff from the facilities where members of the media are staying.

With norovirus being a food and waterborne illness, food workers being confirmed sick is worrying. Food service settings, like restaurants and buffets, account for most outbreaks, as infected people might touch ready-to-eat foods with bare hands. That said, most people infected recover after a few days of rest, but the very young, the elderly and otherwise immunocompromised individuals face higher risks. Symptoms include vomiting, nausea, diarrhea, fever and stomach pain.

In an effort to stop the spread, officials have quarantined anyone who has shown a symptom of food poisoning. Information on virus prevention, as well as hand sanitizer and clean water bottles, are being distributed to visitors, and staff is reinforcing efforts to disinfect surfaces at Olympic facilities.

“In order to stop the further outbreak of the virus, we’re quarantining patients beginning from the diagnosis to the treatment,” said Kim. “We’re going to minimize this outbreak.”