The department is awaiting results of its checks on another five batches of vaccine sent by local manufacturer Siam Bioscience, DMS chief Dr Supakit Sirilak said.
Siam Bioscience delivered the five batches for checking on Tuesday (May 25), with results expected after three days.
Each batch contains between 1 million and 2 million doses. However, the next batches may be increased to 2.5-3 million doses each once the company gains confidence in the product, said Dr Supakit.
The vaccine is being produced by Siam Bioscience via a technology-transfer deal with AstraZeneca.
AstraZeneca has confirmed that the first batch of vaccine will be delivered next month. Mass vaccination in Thailand is due to start on June 7.