The letter, which was sent on Sunday, also said hospitals and medical facilities should be ready to provide treatment to patients under home isolation and community isolation.
The letter was triggered by the number of Covid-19 cases in Thailand rising beyond the 10,000 mark daily.
The letter also called for integration between government and private sectors as well as resource management, which is necessary to effectively contain the spread of Covid-19.
“The department wants medical institutions to use antigen test kits [ATKs] on people at risk of infection and RT-PCR tests when necessary,” it said.
“Meanwhile, patients with mild symptoms should receive treatment under home or community isolation schemes,” the letter concluded.