Dr Yong Poovorawan, head of the Centre of Excellence in Clinical Virology at Chulalongkorn's Faculty of Medicine, said that the cycle threshold in the outbreak is low, meaning asymptomatic patients or those with little symptoms could spread the virus very well.

All suspects now need to test for the virus with RT-PCR method, including those without symptoms.

The government also needs to hasten proactive search in the outbreak areas as quickly as possible, while private hospitals should lower testing price.

Currently, the vaccine is registered in the country of manufacture, both normal or emergency vaccine. There are already six types, hoping that they will be used soon, Dr Yong said.

New Covid-19 outbreak in Thailand still in early stages, expert warns

The current Covid-19 outbreak in Thailand was still in its early stages, a medical expert warned, adding many infected people would have little symptoms or be asymptomatic so they could spread the infection.