There were 6,428 new Covid-19 cases and 49 more fatalities recorded during the previous 24 hours, the Public Health Ministry announced on Monday morning.
There were 5,878 cases in the general population and 553 among prison inmates.
The number of new cases dropped from 7,006 announced on Sunday, when the country recorded 29 more deaths.
On Sunday, 7,882 Covid-19 patients were discharged from hospitals after recovering from the coronavirus.
Since April 1, when the third wave of Covid-19 began, Thailand has treated 2,042,146 Covid-19 patients, 1,937,379 of whom have recovered to date.
Since the pandemic started early last year, there have been 2,071,009 Covid-19 cases, with 1,964,805 complete recoveries so far.
The death toll stood at 20,342 during the third wave and 20,436 since the beginning of the pandemic.
Apisamai Srirangson, a spokeswoman for the Centre for Covid-19 Situation Administration, said in the afternoon briefing that the 49 new fatalities were aged 14 to 95 years and included one Myanmar national and one Vietnamese. The 14-year-old was an unvaccinated child in Pattani province.
Bangkok registered six more deaths while a further two were reported in the adjacent provinces of Samut Sakhon and Samut Prakan.
Other central plain provinces further from the capital recorded 13 more deaths - in Trat (2), Prachuap Khiri Khan (2), Ratchaburi (2), Ang Thong (2), Chanthaburi (1), Chachoengsao (1), Chon Buri (1), Samut Songkhram (1) and Suphan Buri (1).
The Northeast had nine fatalities - in Nakhon Ratchasima (3), Kalasin (1), Chaiyaphum (1), Bung Kan (1), Mukdahan (1), Ubon Ratchathani (1) and Udon Thani (1).
The South reported 14 more deaths – in Songkhla (5), Nakhon Si Thammarat (2), Pattani (2), Phatthalung (2), Chumphon (1), Yala (1) and Satun (1).
The North saw five fatalities – in Chiang Mai (4) and Sukhothai (1).
The 6,428 new cases included 5,868 local infections and 10 imported cases. Of the local infections, 5,732 were confirmed at hospitals and 133 via mass testing.
Bangkok had 815 new cases, followed by 457 in Songkhla, 438 in Nakhon Si Thammarat, 289 in Ratchaburi, 280 in Surat Thani, 240 in Chiang Mai, 194 in Pattani, 164 in Samut Prakan, 150 in Chon Buri and 146 in Yala.
Dr Apisamai said the government was closely following up on outbreaks in the southern provinces of Songkhla, Trang, Surat Thani, Krabi and Nakhon Si Thammarat, which recorded more than 100 new cases a day and over 5% of their antigen tests returned positive.
Also under close watch were Khon Kaen, Sa Kaeo and Nakhon Ratchasima, with more than 100 new cases each but fewer than 5% of antigen tests returning positive daily. Also, Saraburi, Ubon Ratchathani, Udon Thani, Kanchanaburi and Prachuap Khiri Khan, which had 80-100 new cases each daily, she said.
Dr Apisamai also said that new case numbers tended to rise in Chiang Mai, with more than 100 new cases a day, and in Chiang Rai, Lamphun, Phitsanulok and Sing Buri, with fewer than 100 new cases a day each.
The 10 imported cases were from the United Kingdom (1), Belgium (1), Sweden (1), the Netherlands (1), South Korea (1), Egypt (1), Malaysia (3) and Cambodia (1).
Since the country reopened to visitors on Nov 1, 85,608 people arrived by air and 112 of them (0.13%) were confirmed with Covid-19, as of midnight.
On Sunday 85,768 people received Covid-19 treatment at hospitals, including 1,595 seriously ill patients and 382 dependent on ventilators.
Global Covid-19 cases rose by 386,888 in 24 hours to 257.82 million. The worldwide death toll went up by 4,114 to 5.16 million.
The United States had the most cases at 48.59 million, up 27,484, and the most deaths at 793,651, up 96.
Dr Apisamai quoted the World Health Organization as reporting high increases in new cases in America and Europe. New cases, seriously ill patients and fatalities were rising in eastern Europe, where vaccinations were limited, she said.
“Thailand must monitor the situation closely because visitors to Thailand come mainly from Europe and the US,” she said.
