The government reported a single new case of the novel coronavirus on Monday, a 29-year-old British woman, raising the accumulated total in Thailand to 3,412.
The Centre for Covid-19 Situation Administration said the woman was a language teacher who arrived in Thailand with her husband and daughter on Aug 15 and underwent alternative state quarantine in Bangkok.
The result of her second test for Covid-19 on Thursday was positive. She had a fever and headache, the centre said.
No new fatalities were reported on Monday, leaving the accumulated death toll in Thailand at 58.