This clinical trial is aimed to evaluate the immunogenicity, safety and immune persistence of recombinant trivalent rotavirus subunit vaccine in Chinese healthy infants aged 6-12 weeks and healthy toddlers aged 7-71 months.The subjects will be divided into 12 subgroups. Two different immune regimens and two dose levels will be evaluated in each age group. Toddlers aged 7-71 months will receive two intramuscular injections on Day 0 and 28 or three intramuscular injections on Day 0, 28 and 56. Infants aged 6-12 weeks will receive three intramuscular injections on Day 0, 28 and 56 or Day 0, 56 and 112. Two dose (mid dose and high dose) will be included in each age group. To maintain blindness in the trial, in each age group with fixed immune regimen, subjects will be randomized in a 1:1:1 ratio to receive mid dose vaccine, high dose vaccine, or placebo.
The purpose of this study is to assess the immunogenicity, safety and immune persistence of recombinant trivalent rotavirus subunit vaccine in healthy infants aged 6-12 weeks and healthy toddlers aged 7-71 months.