Samut Sakhon, Chiang Mai and Tak will start vaccinating priority groups, including health workers, against Covid-19 from March 1.
The first 317,000 doses of Covid-19 vaccines -- 200,000 from Chinese pharmaceutical company Sinovac and 117,000 from British-Swedish pharmaceutical company AstraZeneca -- arrived in Thailand on Wednesday.
The first 200,000 Sinovac doses will be inspected by officials from the Food and Drug Administration (FDA) and Government Pharmaceutical Organisation (GPO) for three days.
The vaccines will then be given to priority groups in 13 provinces with the highest infection rates, the greatest economic significance, or both. More than half of the Sinovac batch will be earmarked for Samut Sakhon, the epicentre of Thailand's latest outbreak, and Bangkok.
Samut Sakhon, which will receive 70,000 doses of Sinovac, has announced it will next month start vaccinating healthcare personnel in contact with infected people and those with chronic diseases.
Dr Naresrit Katasrima, head of Samut Sakhon's Public Health Office, said about 4,000 people would be vaccinated per day at three public hospitals and seven private hospitals in the province, so it would take 17-20 days to administer all 70,000 doses it receives. It will take 5-7 minutes per recipient, who must then wait for 30 minutes while their condition is monitored.
Chiang Mai, which will receive 3,500 Sinovac doses, has also announced plans to begin vaccinating priority groups next month.
Dr Jatuchai Maneerat, head of Chiang Mai's Public Health Office, said the province planned to vaccinate 1,750 healthcare workers on March 1 and 41,750 people would be vaccinated by May. About 5,000 medical and health personnel will also be vaccinated in Mae Sot on March 1.
The first Covid-19 jab to be administered in Thailand will be given to Prime Minister Prayut Chan-o-cha on Sunday and it will be the AstraZeneca version.
Gen Prayut called the arrival of the first Sinovac vaccines a historic moment and he thanked all those involved for making it happen. "Today is a historic day," he said. "The government has tried its best to receive the vaccines as scheduled. Without any unexpected problems, we will have enough to develop herd immunity."