Children should be vaccinated against HFMD between the ages of six months and five weeks after birth because they are susceptible to HFMD at this age and can develop serious complications. Children in this age group have a low immune system, and infection with HFMD can lead to serious complications such as neurogenic pulmonary edema and myocarditis, and can even cause death. The HFMD vaccine is mainly developed for EV71 enterovirus, which causes severe HFMD, mostly due to EV71 infection in children, and the coxsackie virus of the enterovirus mostly causes mild HFMD.