A new case of coronavirus was found on Friday, the first to affect a health worker, bringing the total in the country to 34 since January.
The new case is a 35-year-old woman, who contracted the disease from contact with a patient, Dr Suwanchai Wattanayingcharoenchia, the director-general of the Department of Disease Control, told a news conference on Saturday.
An investigation found she did not wear a mask and protective suit while treating a patient, who was at the time diagnosed with another disease.
The patient later demonstrated a fever, coughing and exhaustion and was later found to have been infected with COVID-19, the official name of the coronavirus.
Twenty-four colleagues of the woman who were also at risk tested negative and showed no symptoms. No family members were at risk either because she lived in a dormitory.
The department said in a statement that the woman worked at a private hospital, not at the Bamrasnaradura Infectious Diseases Institute, where most virus patients are being treated.
After she tested positive, she was sent to the institute, which is well equipped to handle infectious diseases, according to the statement.
On Friday, a female Chinese tourist, 56, was discharged, bringing the total number of cleared patients to 14, with 20 remaining at the hospital, Dr Suwanchai said.
Two of those still in hospital were in critical condition. One showed severe respiratory symptoms and is now on extracorporeal membrane oxygenation (ECMO) and a respirator. The other was also infected with tuberculosis, he said.
Both received convalescent plasma — plasma from survivors of the virus — to help with the treatment. They remain stable with slightly improved blood oxygen circulation rates.
Other patients are recovering, he added.
The doctor stressed the virus is contracted through mucous mist. A person at risk must be within 1-2 metres from the infected person while he or she is coughing or sneezing or come into contact with secretions through mucous membranes in the mouth, eyes or nose, hence the need to wash hands frequently.
Over 1,500 people in China have died from the virus but Thailand has not recorded a fatality so far.
Health personnel are one of the most vulnerable groups. Bejing revealed on Friday that 1,716 medical workers have been infected during the outbreak, with six dying from the illness.
Most of the infections among health workers were in Wuhan, where many people have lacked proper masks and gear to protect themselves in hospitals dealing with a deluge of patients.