Objective  To evaluate the safety and immunogenicity of an inactivated poliovirus vaccine made from Sabin strains (sIPV).

  Methods  In Dafeng county of Jiangsu province, China, we recruited healthy infants aged 2 months for clinical trials between August 2017 and April 2018. In a phaseⅠb clinical trial, 20 participants received the high-dose sIPV. In another phaseⅠclinical trial, 60 participants were randomized into three groups at a ratio of 1:1:1 to receive one of the three different vaccines: the low-dose sIPV, the control sIPV, or the IPV made from wild-type strains (wIPV). Follow-up observations on adverse effects after the vaccinations were conducted among all the participants and serum samples of the participants were obtained before the first dose and the day 30 after the full dose immunization for microneutralization assays.

  Results  The overall incidence of reported adverse effects after 3 dose vaccinations in the groups of high-dose sIPV, low-dose sIPV, control sIPV and control wIPV were 70.0%, 55.0%, 65.0% and 50.0%, respectively. The majority of the adverse effects were all of grade I (mild). After the 3 dose vaccinations, the geometric mean titer (GMT) of the microneutralization antibodies in the groups of high-dose sIPV, low-dose sIPV, control sIPV and control wIPV were 2 007.47, 2 070.22, 1 580.56 and 364.70 for poliovirus type 1; 700.26, 477.52, 220.98 and 159.75 for poliovirus type 2; 366.21, 522.75, 289.64 and 306.74 for poliovirus type 3, respectively.

  Conclusion  Both the low-dose and high-dose sIPV showed a good safety and a better immunogenicity compared with the other two control vaccines when used among 2-month old infants.