Safety and immunogenicity of inactivated poliovirus vaccine made from Sabin strains: A phase II, randomized, dose-finding trial.

BACKGROUND

In order to completely eradicate polio caused by wild poliovirus infection as well as vaccine-associated paralytic polio (VAPP), Sabin inactivated poliovirus vaccine (sIPV) should be developed to meet the requirements for biosafety and affordable strategy in the developing countries.

METHOD: A randomized, double-blinded clinical trial was conducted to compare the immunogenicity and safety among infants aged 2 months (60-90 days) receiving five different vaccination regimens: the test groups (A, B, and C) received three doses of sIPV with high, medium, and low D antigen content, respectively, on the month 0, 1, 2 schedule; two control groups (D and E) received three doses of conventional IPV (cIPV) or sIPV (CAMS), respectively, on the same schedule as that of test groups. Serum samples were collected immediately before the 1st dose and 30 days after the 3rd dose vaccination to assess the immunogenicity. Adverse events occurring within 30 days after each dose were collected to assess the safety.

RESULTS

After three doses, seroconversion rates in groups A-E were 100%, 98.2%, 100%, 100%, and 100%, respectively, for type 1; 99.1%, 100%, 98.1%, 100%, and 97.1%, respectively, for type 2; and 100%, 100%, 100%, 100%, and 99.0%, respectively, for type 3. The seropositive rates (≥1:8) of groups A-E for all types were nearly 100%. The GMTs in the target dose group (group B) were 4635, 342, and 2218 for type 1-3, respectively. The most common injection-site and systemic adverse reactions were swelling and fever respectively. The swelling (4.2%, P = 0.0075) and fever (58.3%, P = 0.0188) frequency of group A were statistically significantly higher than any other groups.

CONCLUSION

The test sIPV generally demonstrated good safety and immunogenicity. The medium-D antigen dose would be a preferred choice for the further phase III clinical trial in consideration of its high immunogenicity for all serotypes and the satisfying tolerance.

CLINICAL TRIALS REGISTRATION: NCT02985320.