The Bangkok Metropolitan Administration (BMA)’s public health office reported on Sunday that the first two patients had tested positive on March 19.
"So we began the tracing immediately,” said Chawin Sirinak, BMA deputy permanent secretary.
“So far, 28 people have tested positive from a total of 215 people who had close contact with the patients.”
Of the total 215 at risk, 37 people were classified as having high risk while 178 had low risk of infection.
“We have ordered all the people at risk to remain in self-quarantine and monitor their symptoms closely, while a cleaning team has been dispatched to the factory to clean up and disinfect the area,” added Chawin.
The BMA will also dispatch more mobile testing units to widen the tests to cover the communities around the factory.