Vietnam says a large ongoing outbreak of a common childhood virus could worsen this year.
The hand, foot and mouth virus has sickened more than 6,000 and killed nine children since January. They died from the strain EV-71, a more virulent enterovirus.
The Health Ministry said this year's infection rate is seven times higher than it was during the first six weeks of 2011. But it has slowed since a September peak of 3,000 cases per week.
State media reported the health officials' comments on Tuesday.
Last year, the disease sickened more than 110,000 and killed 166, mostly children. The common disease typically causes little more than a fever and rash. No vaccine exists.