Ten kindergartens in Hau Giang province were shut for 10 days to clean and check the students' health, said Nguyen Van Muoi, head of the provincial preventive medicine center. Four schools reopened last week, he added.
The southern province has had 361 cases since June, and some 50 children are hospitalized. He blamed the increase on the virus' spread after children returned to school from summer break.
"I hope with this measure (closing the preschools), the new cases will drop," Muoi said.
At least three more kindergartens in the southern Bac Lieu province and the central highland province of Dak Nong also have been closed, Monday's Vietnam News reported.
The Health Ministry says more than 2,000 new cases of hand, foot and mouth disease are being reported each week. In a typical year, the virus infects up to 15,000 children in Vietnam and kills 20 to 30 of them.
The Health Ministry has recorded 52,321 cases and 109 deaths in the country as of Sept. 15. A more severe strain called enterovirus 71, or EV-71, was identified earlier in about a third of sampled cases. It can result in paralysis, brain swelling and death.
The World Health Organization has said three-quarters of the deaths have been children younger than 3 years old.
The virus is named from its telltale symptoms, including rash, mouth sores and blisters on the hands and feet. It is spread by sneezing, coughing and contact with fluid from blisters or infected feces.
No vaccine exists, but the illness is typically mild and most children recover quickly. The disease is caused by enteroviruses in the same family as polio.