The four returnees from Wuhan who were hospitalised with a fever have all recovered, but one still requires treatment for a lung disorder.
RAdm Kerdsak Weerayothin, director of Queen Sirikit Hospital in Chon Buri province, said on Thursday that four returnees had been admitted with a fever, coughing and diarrhoea and their symptoms had now subsided.
However, x-rays revealed one of them had a small lung disorder. The patient would be thoroughly examined, he said.
Initial tests did not find any novel coronavirus infection. The tests would be repeated for subsequent confirmation, he said.
The other 134 returnees are at the Sattahip naval base in Chon Buri.
Dr Suthep Phetmak, an inspector-general of the Public Health Department, said they remained healthy. Three of them had developed symptoms of tension and anxiety and had received psychiatric counselling and medication.
Navy spokesman VAdm Prachachart Sirisawat said there were 30 male and 104 female returnees at the base, aged from six months to 53 years.
Their phones has been decontaminated, so they could use them to contact friends and relatives.
Dr Tanarak Plipat, deputy director-general of the Disease Control Department, said the number of infections detected in Thailand remained at 25. Nine had been discharged from hospitals. The number of patients being monitored for infection had risen to 595.
"Transmission inside the country is still limited, as in many other countries. There is still a chance of finding visitors with symptoms, and people in contact with them. If all ill people are identified there will be only a small number of infected people on the outside," he said.
"In summary, Thai people have a very low risk of contracting the virus. I recommend frequent hand washing and the use of face masks," Dr Tanarak said.
Government spokesperson Narumon Pinyosinwat said Prime Minister Prayut Chan-o-cha ordered government organisations to hand out face masks in Bangkok and major provinces through until Saturday to help with disease control.