On Apr. 16, 2019, Sinovac Biotech announced that the positive results from the Company’s Phase III clinical study of a Sabin strain-based inactivated polio vaccine (sIPV) developed by Sinovac were published in the Journal of Infectious Disease. With Sinovac’s sIPV, efficacy was maintained while common risks associated with legacy vaccines can be mitigated. In comparison to oral polio vaccine (OPV), inactivated polio vaccine (IPV) contains no live virus and thus carries no risk of vaccine-derived poliovirus (VDPV) emergence or vaccine-associated paralytic polio.

This research implies that the studied sIPV is as effective as IPV in preventing poliovirus infection in infants aged 60–90 days, can be a reliable alternative to conventional IPV and can be a good supplement to OPV in potentially preventing or minimizing VDPV emergence or VAPP. Participants in the sIPV arm of the trial developed neutralizing antibodies against poliovirus types 1, 2, and 3 with seroconversion rates of 98.0% against type 1 poliovirus, 94.8% against type 2, and 98.9% against type 3. Seroconversion rates were higher in the sIPV arm than in the IPV arm against all three types, significantly so against types 1 and 2. Participants in the IPV arm developed neutralizing antibodies against poliovirus types 1, 2, and 3 with seroconversion rates of 94.1% against type 1, 84.0% against type 2, and 97.7% against type 3.

This study was a randomized controlled, double-blinded, noninferiority trial investigating the immunogenicity and safety of Sinovac’s sIPV. The study enrolled 1200 healthy infants ages 60-90 days that were randomly assigned at a ratio of 1:1 to receive 3 doses of either sIPV or IPV at days 0, 30, and 60. The safety of the vaccine was assessed for 30 days after each injection. The study was conducted in Pizhou City and Guanyun County in Jiangsu Province, China, from August 2017 to January 2018.