Vaccination against hand, foot and mouth disease (EV71 vaccine) is best started as early as possible when the child is 6 months old, and is not recommended if the child is older than 5 years. This is because the level of antibodies acquired from the mother decreases gradually after the child is born, especially dropping to a minimum between 5 and 11 months of age. Therefore, the highest risk of HFMD infection in infants and children is at the age of 5 years. If vaccination is started at the age of 6 months, then it will provide timely and effective protection for susceptible children. And beyond 5 years of age, the chances of children getting HFMD again will be low, so there will be no need for EV71 vaccine. However, it is important to know that the vaccine does not guarantee that children will not get HFMD, but it will reduce the risk of getting HFMD, especially the risk of getting severe HFMD.