Rotavirus vaccine (Sinovac Biotech)

Primary objective: To evaluate the safety of rotavirus vaccine in healthy adults, children and infants; Secondary objectives: To evaluate the safety of rotavirus vaccine in healthy adults, children and infants; To evaluate the immunogenicity and immune persistence of rotavirus vaccine in healthy infants; To evaluate the fecal excretion of rotavirus vaccine in healthy infants after rotavirus vaccine vaccination; To evaluate the reassortment and reversion of rotavirus vaccine strains in fecal samples of healthy infants after rotavirus vaccine vaccination.