The Ministry of Public Health will give the first round of Pfizer's Covid-19 vaccine to children aged five to 11 on Monday.
Dr Opas Karnkawinpong of the Department of Disease Control said healthy children should get the vaccine at school if possible.
Most healthy kids should wait between eight to 12 weeks before getting their second dose of Pfizer, he said.
"We are ready to kick off the Covid-19 vaccine for kids on Jan 31 at the the Queen Sirikit National Institute of Child Health. Children suffering from chronic diseases will be our first priority," Dr Opas said, adding Thailand is only the second country after Singapore in Asia to receive Pfizer shots for kids.
According to the ministry, there are 5 million children aged five to 11 years in the country, some of whom live with chronic diseases.
The ministry has ordered 10 million doses of Pfizer's mRNA-based vaccine, with just over a third expected to arrive in the first quarter.
The Royal College of Paediatricians of Thailand said there are fewer side effects among children compared to adults due to the smaller amount of vaccine given.