A total of 900 subjects are planned to be randomly divided into 2 doses of low-dose experimental vaccine group, 2 doses of high-dose experimental vaccine group, 2 doses of placebo group, 3 doses of low-dose experimental vaccine group, 3 doses of high-dose experimental vaccine group and 3 doses of placebo group, the sample size of each group was 150 cases.~Subjects in the 2 dose group were injected with 2 doses of test vaccine or placebo in the upper arm deltoid muscle according to the 0,1 month immunization program, and subjects in the 3 dose group were injected with 3 doses of test vaccine or placebo in the upper arm deltoid muscle according to the 0, 1, 2 month immunization program .
A total of 900 subjects are planned to be randomly divided into 2 doses of low-dose experimental vaccine group, 2 doses of high-dose experimental vaccine group, 2 doses of placebo group, 3 doses of low-dose experimental vaccine group, 3 doses of high-dose experimental vaccine group and 3 doses of placebo group, the sample size of each group was 150 cases.