At a news conference on Wednesday night, Dr. Park Kisoo, a spokesman for the Korea Centers for Disease Control and Prevention, tried to temper the growing sense of worry here.

“You don’t need to go running out of the room if somebody sneezes,” Park said.

Park preached the importance of proactive personal hygiene. So along with wool caps and long underwear, bottles of hand sanitizer in varying shapes and sizes have become this year’s hottest Olympic accessory.

Never mind the studies showing they are largely ineffective in battling norovirus.

“The U.S.O.C. physician said that the antibacterial spray does not kill the norovirus,” said Matt Hamilton, an American curler competing in the men’s and mixed-doubles events, using the acronym for the United States Olympic Committee. “But what does do a good job is the Ivory soap. So he’s just like, ‘Soap up.’ ”

The buses that constitute the Olympics’ internal transportation network have been running smoothly on schedule. The facilities, and the hospitality of those staffing them, have won early raves.

But the pesky virus has threatened to derail some of the early good vibes.

More than a thousand people have been quarantined as organizers have rushed to halt the spread of the virus, which can cause bouts of vomiting, diarrhea and abdominal pain. The military was called in to provide additional support to the decimated staff.

So far 97 of the cases have been at Horeb Youth Centre, a dormitory that housed many local security staff members; 11 were in Pyeongchang; 20 were in Gangneung.

Kimani Griffin, an American speed skater and first-time Olympian, said these sorts of outbreaks were always a possibility at major international sporting events, where visitors from around the globe are gathered into tight quarters, day after day.