The virus is also becoming a seasonal concern, officials at the department said.
"According to the department's division of epidemiology, Covid-19 is spreading seasonally like the flu," said department director-general Dr Tares Krassanairawiwong.
He also expects Covid-19 to spread more during the rainy season.
"The Public Health Ministry would like to ask people to receive their Covid-19 vaccine jab before the rainy season begins," Tares said.
The ministry will conduct annual vaccinations for the first time this year, he said.
"People can receive any Covid-19 vaccine at least three months after the last dose or infection," he said, adding that they do not need to count the number of doses received so far.
People can receive a Covid-19 jab at provincial public health offices nationwide, he said.
Meanwhile, the department’s deputy director-general Dr Sopon Iamsirithaworn said the ministry's plan to conduct annual vaccination came after two studies showed that most Thais already have immunity against the virus.
The studies were conducted by the department's division of epidemiology and Chulalongkorn University's top virologist Dr Yong Poovorawan, Sopon added.
"We recommend people receive a Covid-19 jab annually," he said.
He also pointed out that people in the so-called “608 group” – those 60 or older or with any of the eight underlying ailments – service workers, people living in confined areas, medical staff, and children under five years of age should receive a Covid-19 jab to reduce the risk of death or developing severe symptoms.