Answer:

The severity of a recurrent hand, foot, and mouth disease infection depends on the virus strain, the child's age, immune status, and the approach to detection and care.

The disease is caused by various enteroviruses, most commonly Coxsackie A16, A6, A10, and Enterovirus 71 (EV71). EV71 itself has multiple subgroups (B4, B5, C4, C1, etc.), meaning immunity after a first infection provides protection primarily against that specific subgroup, but not fully against others. Therefore, children can be re-infected if they contract a different subgroup.

Disease severity varies by pathogen: A16 typically causes mild illness; A6 leads to high fever and widespread rash; EV71 is often associated with severe cases and neurological or cardiopulmonary complications such as encephalitis, meningitis, pulmonary edema, and cardiopulmonary failure. A large study in China indicated that children re-infected with EV71 or other enteroviruses faced a much higher risk of severe illness compared to those re-infected with A16.

Young children, especially those under three, malnourished children, or those with underlying conditions or compromised immunity, are more susceptible to severe progression. Conversely, healthy children who are diagnosed early and receive proper care typically recover better, though parents still need to monitor them closely.

Children who have had hand, foot, and mouth disease can still be re-infected. *Vecteezy*

Improper care can worsen the disease: this includes self-administering antibiotics, incorrect antipyretic dosing, avoiding bathing, overtight swaddling, applying unknown herbal remedies or solutions, or allowing the child to become dehydrated due to painful mouth sores. More dangerously, assuming "it's already been contracted, so this time it will be mild" and overlooking warning signs can lead to delayed hospitalization when neurological or cardiopulmonary complications have already developed.

When a child contracts hand, foot, and mouth disease for a second time, parents should seek medical attention and monitor them closely during the initial days, even if the rash is minimal. Children need rest, sufficient hydration, soft and cool foods, and antipyretics administered as directed. Do not puncture blisters or apply medication indiscriminately. Seek immediate medical care if the child experiences: prolonged high fever, sudden startling, trembling limbs, drowsiness, excessive vomiting, limb weakness, rapid or unusual breathing, or cold hands and feet.

Currently, there is no specific treatment for the disease, but an EV71 vaccine was approved in 3/2026. The vaccine is for children from two months to under six years old. VNVC Immunization System, a comprehensive strategic partner with Swiss pharmaceutical group Biologics Substipharm, the vaccine distributor in Vietnam, is coordinating efforts to make the vaccine available soon.

Dr. Nguyen Tien Dao

Medical Manager, VNVC Immunization System

Readers can submit vaccine-related questions for the doctor to answer here.