The Centre for Health Protection has identified six clusters of suspected food poisonings, affecting seven men and nine women, who ate Horng Ryen Jen sandwiches.
The 16 patients, aged three to 69, fell ill after consuming the sandwiches ordered online, bought from exhibition booths in Kowloon City and Ma On Shan, and from a supermarket in Kowloon Bay from July 26 to 29.
Ten sought medical consultation, four required hospitalisation and three have been discharged.
The centre will liaise with Taiwan authorities and the local trade to trace the source of the contaminated food.
The Centre for Food Safety urged the public not to consume the product. The trade should also stop selling it.