According to the Dong Nai Health Department, as of 11am May 3, hospitals in Dong Nai had received 469 patients, including 12 children, with similar food poisoning symptoms.
"All the victims had banh mi sandwiches at the Bang Bakery in Xuan Binh Ward between 3-7 pm on April 30," the department said. "After that, they started to develop high fevers, stomach aches, diarrhoea, and vomiting and had to be hospitalised.
Five children treated at the Dong Nai Children's Hospital are in critical condition and two of them have received hemofiltration.
Doctors at the Long Khanh General Hospital said that they admitted 321 of these food poisoning cases, and all the victims had gastroenteritis, and many were recovering after treatment.
The bakery that sold over 1,100 banh mi sandwiches on April 30 has been closed for investigation since May 1.
Last year, nearly 300 people had food poisoning after eating banh mi sandwiches at the well-known Madam Phuong Bakery shop in Hoi An City.
The Vietnamese banh mi baguette, filled with cold meats, pâté, and vegetables, is a popular snack in Vietnam.