Strict quarantine was in effect after more than 130 freshmen of Udon Thani Rajabhat University were infected with influenza after freshmen welcoming activities.
A field hospital was set up by Udon Thani Provincial Health Office and Udon Thani Hospital in a female dorm at the university.
The field hospital has quarantined the most ill patients and is monitoring their condition after 134 freshmen came down with flu symptoms.
It was reported that the sick students suffered fever, sore throats, and headaches.
Three students were in serious condition and were transferred to Udon Thani Hospital for treatment.
Doctors subsequently kept those with moderate symptoms at the field hospital, with the rest ordered to rest in their dorm rooms.
Head of Udon Thani Provincial Health Office, Dr Smiths Prasannakan, said an investigation found that all of the sick students had attended freshmen welcoming activities, which included eating and drinking together