The fifth round vaccine is necessary. The fifth round vaccine is usually an oral pentavalent reconstituted live attenuated rotavirus vaccine. The rotavirus vaccine stimulates the body to develop immunity against rotavirus and prevents rotavirus enteritis. Rotavirus infection occurs most often in children between the ages of six months and three years, and can cause acute gastroenteritis, which is highly contagious and is accompanied by symptoms such as abdominal pain, fever, and egg-like stools. The effect of drug treatment of rotavirus infection is limited, mainly need to carry out symptomatic treatment, some patients in addition to abdominal pain, fever and other symptoms, serious cases will appear shock situation, need to be treated as soon as possible. Vaccination against rotavirus is a more effective way of prevention. Because rotavirus infection is mostly seen in infants and younger children, their own resistance and immunity is relatively poor, so their physical condition and anti-virus ability are relatively poor, so they need to be vaccinated to improve anti-virus ability. The vaccine is needed to improve their resistance to the virus and to avoid the more serious consequences of infection.