Of the total, 2,563 were local patients who went to hospitals for testing, 1,352 were found during proactive search, 45 were found in prisons, and 35 were travellers from abroad.
Bangkok led the list of most cases with 1,370, followed by Samut Sakhon (289), Samut Prakarn (231), Nonthaburi (195), and Pattani (189).
Meanwhile, 2,253 patients have recovered and been discharged in the last 24 hours.
As of Sunday, the number of confirmed cases in Thailand had risen to 215,584.
So far, 198,928 have recovered and been discharged, 43,607 patients are still in hospitals, and 1,912 have died.
According to Worldometer, as of 11am on Sunday, the number of confirmed cases globally had risen to 181.56 million (up by 368,541), 166.08 million of whom have recovered, 11.46 million are active cases (80,670 in severe condition) and 3.93 million have died (up by 7,526).
Thailand ranks 76th on the global list of most cases, which is topped by the US with 34.49 million, followed by India 30.23 million, Brazil 18.39 million, France 5.77 million, and Russia 5.43 million.
Meanwhile, another 40,930 people were given their first Covid-19 shot in the last 24 hours, while 33,145 people were given their second shot, bringing the total number of Covid-19 vaccine doses administered in Thailand to 9,055,141.