The disease broke out in April 2011 and progressed to more than 15,218 cases currently reported -- seven times more than last year's figure, the Red Cross said.
The disease began in the Ba To District of Quang Ngai province.
Le Han Phong, chairman of Ba To People's Committee, said at first authorities were aware of the mounting death toll. Another party official was uneducated as to its cause, Thahn Nien reported.
"We know about the deaths, but because we were yet to identify their causes, we did not report them for fear of scaring local people," said Dang Thi Phuong, director of Ba To's health center.
The Red Cross says the virus' symptoms include fever, blisters on the hands and feet, and sores in the mouth. No specific treatment exists for the disease, but people can cut down the risk of catching the virus by practicing good hygiene.
"Action is needed now to introduce improved hygiene practices in at-risk communities ahead of the usual two high seasons for the disease, in April-May and September-October," the International Federation of Red Cross and Red Crescent's representative in Viet Nam, Bhupinder Tomar, said.