BANGKOK: Thailand's health ministry said on Sunday more than 600 medical workers who received two doses of China's Sinovac vaccine have been infected with COVID-19, as authorities weigh giving booster doses to raise immunity.

Of the 677,348 medical personnel who received two doses of Sinovac, 618 became infected, health ministry data from April to July showed. A nurse has died and another medical worker is in critical condition.

An expert panel has recommended a third dose to trigger immunity for medical workers who are at risk, senior health official Sopon Iamsirithawon, told a news briefing on Sunday.

"This will be a different vaccine, either viral vector AstraZeneca or an mRNA vaccine, which Thailand will be receiving in the near term," he said, adding that the recommendation will be considered on Monday.

The announcement comes as the Southeast Asian country reported a record high of 9,418 community infections on Sunday. On Saturday authorities reported a record of 91 new daily coronavirus fatalities.

Thailand has reported a total of 336,371 confirmed infections and 2,711 fatalities since the pandemic began last year.

The majority of Thailand's medical and frontline workers were given Sinovac's shots after February with the viral vector vaccine from AstraZeneca arriving in June.

Thailand is expecting a donation of 1.5 million Pfizer-BioNTech vaccines from the United States later this month and has ordered 20 million doses that will be delivered after October.

Neighbouring Indonesia, which has also heavily relied on Sinovac, said on Friday it would give the Moderna vaccine as boosters to medical workers.