Chulalongkorn University virology specialist and chief of the Centre of Excellence in Clinical Virology, Dr Yong Poovorawan, said in a Facebook post on Sunday that research had been done on five samples.
"However, in practice, receiving different brands of Covid-19 vaccine is not recommended because it is a new vaccine," he said.
According to the research, four samples who received first the Sinovac vaccine and the second dose of AstraZeneca had higher immunity than people who received both shots of Sinovac.
Meanwhile, one sample who received AstraZeneca first and then Sinovac also had higher immunity than the average.
Dr Yong added that the centre would continue its research based on safety, as it would be another way to use Covid-19 vaccines amid the vaccine shortage, or stimulate immunity after receiving the second shot.