The cluster was sparked by a two-year-old who had been infected by her mother.
The youngster’s mum works in Chonburi and had come over for a week. She also infected her parents, who live in the same house.
So far, 10 children and two teachers have been transferred to Srinagarind Hospital for treatment, while another 24 children and six teachers have been sent to Khon Kaen Hospital.
Meanwhile, provincial disease investigation officials say the Covid-19 virus detected in these patients appears to be a new variant.
“We have tested 300 people who have been in contact with these patients and have urged people travelling from provinces under maximum and strict control to report to the nearest public health office,” an official said.