This study includes two stages. A clinical trial with an open-label to evaluate the safety of Sabin Inactivated Poliovirus Vaccine (Vero cell) (2.5ml-5 doses) (hereinafter referred to as "msIPV") in adults, children and infants in stageⅠ and a blinded, randomized and controlled clinical trial to evaluate the lot consistency immunogenicity, and safety of the msIPV in 2 months old infants in stage Ⅱ. A total of 1572 subjects including 24 adults aged 18-49 years,24 children aged 4 years,1524 infants aged 2 months will be enrolled.
StagesⅠ:72 healthy subjects, including 24 adults,24 children and 24 infants will be enrolled. 24 adults and 24 children will receive one dose of vaccine and 24 infants will receive 4 doses of vaccine according to the primary immunization schedule of 0,1,2 months and booster immunization schedule of 18 months.
StagesⅡ:1500 infants aged 2 months will be randomly divided into 5 groups (Experimental Vaccine-lot 1, Experimental Vaccine-lot 2, Experimental Vaccine-lot 3,IPV control group and single-dose sIPV control group) according to the ratio of 1:1:1:1:1. Subjects in 3 experimental groups will receive 5-dose sIPV produced by Sinovac for three lots, subjects in IPV control group will receive IPV produced by Pasteur, and subjects in single-dose sIPV control group will receive single-dose sIPV produced by Sinovac. All subjects will receive 4 doses of experimental or control vaccine according to the primary immunization schedule of 0,1,2 months, one dose of booster at 18 months of age.