Immune persistence after different polio sequential immunization schedules in Chinese infants.

Trivalent oral poliovirus vaccine (tOPV) has been withdrawn and instead an inactivated poliovirus vaccine (IPV) and bivalent type 1 and type 3 OPV (bOPV) sequential immunization schedule has been implemented since 2016, but no immune persistence data are available for this polio vaccination strategy. This study aimed to assess immune persistence following different polio sequential immunization schedules. Venous blood was collected at 24, 36, and 48 months of age from participants who had completed sequential schedules of combined IPV and OPV in phase III clinical trials. The serum neutralizing antibody titers against poliovirus were determined, and the poliovirus-specific antibody-positive rates were evaluated. A total of 1104 participants were enrolled in this study. The positive rates of poliovirus type 1- and type 3-specific antibodies among the sequential immunization groups showed no significant difference at 24, 36, or 48 months of age. The positive rates of poliovirus type 2-specific antibody in the IPV-IPV-tOPV group at all time points were nearly 100%, which was significantly higher than the corresponding rates in other immunization groups (IPV-bOPV-bOPV and IPV-IPV-bOPV). Immunization schedules involving one or two doses of IPV followed by bOPV failed to maintain a high positive rate for poliovirus type 2-specific antibody.

Immunogenicity of Two Different Sequential Schedules of Inactivated Polio Vaccine Followed by Oral Polio Vaccine Versus Oral Polio Vaccine Alone in Healthy Infants in China.

BACKGROUND: Two vaccination schedules where inactivated polio vaccine (IPV) was followed by oral polio vaccine (OPV) were compared to an OPV-only schedule. METHODS: Healthy Chinese infants received a 3-dose primary series of IPV-OPV-OPV (Group A), IPV-IPV-OPV (Group B), or OPV-OPV-OPV (Group C) at 2, 3, and 4 months of age. At pre-Dose 1, 1-month, and 14-months post-Dose 3, polio 1, 2, and 3 antibody titers were assessed by virus-neutralizing antibody assay with Sabin or wild-type strains. Adverse events were monitored. RESULTS: Anti-polio 1, 2, and 3 titers were ≥8 (1/dil) in >99% of participants, and Group A and Group B were noninferior to Group C at 1-month post-Dose 3 as assessed by Sabin strain-based assay (SSBA). In Group A 1-month post-Dose 3, there was no geometric mean antibody titers (GMT) differences for types 1 and 3; type 2 GMTs were ≈3-fold higher by wild-type strain-based assay (WTBA) versus SSBA. For Group B, GMTs were ≈1.7- and 3.6-fold higher for types 1 and 2 via WTBA, while type 3 GMTs were similar. For Group C, GMTs were ≈6.3- and 2-fold higher for types 1 and 3 with SSBA, and type 2 GMTs were similar. Antibodies persisted in >96.6% of participants. Adverse event incidence in each group was similar. CONCLUSIONS: A primary series of 1 or 2 IPV doses followed by 2 or 1 OPV doses was immunogenic and noninferior to an OPV-only arm. SSBA was better at detecting antibodies elicited by OPV with antibody titers correlated to the number of OPV doses (NCT01475539).

[Study on safety and immunogenicity of oral poliomyelitis attenuated live vaccine (human diploid cell)].

OBJECTIVE: To evaluate the safety and Immunogenicity of the Poliomyelitis vaccine (Human Diploid Cell) in > or =2 month-old children. METHODS: A random, blind and control trial, 1200 healthy children of 2-5 months old in Jiangsu province were administered OPV (HDC) vaccine and control vaccines. The antibody was tested by neutralization test. RESULTS: After 3 doses of the OPV (HDC) vaccine, the systemic reactions were mild. After 1 month of vaccination with 3 doses of the OPV (HDC) vaccine, the immune success rates of I, II, III type were 98.28%, 99.45%, and 95.71% respectively, the GMTs of I, II, III type in susceptible children were 1:1243.72, 1:234.38 and 1:273.10 respectively. CONCLUSIONS: The OPV (HDC) vaccine was safe and immunogenicity for the children > or =2 months old.

[Effectiveness of inactivated poliomyelitis vaccine for primary vaccination].

OBJECTIVE: To study the immunological effectiveness of inactivated poliomyelitis vaccine (IPV) for children's primary vaccination in China and to compare with the oral poliomyelitis vaccine (OPV) used in routine vaccination. METHODS: The 2-month-old children were randomly immunized with IPV and OPV, with 208 subjects in each group. The pre- and post-vaccination blood samples were collected. Micro-neutralization method was used to measure the antibody response against 3 types of polioviruses. chi2 test was used to evaluate the statistical difference of protection rates between two groups, while the antibody titers were transformed by logarithm and analyzed by Z-test. P < 0.05 was always used to define the significance of analysis. RESULTS: After 3 doses of immunization, the protection rates in IPV group reached to 100.0% (186/186), 97.3% (181/186), 98.9% (184/186) for poliovirus type 1, 2, 3, respectively, and in OPV group were 97.4% (188/193), 100.0% (193/193), 95.3% (184/193), respectively. The geometry mean titers (GMTs) were 151.2, 86.7, 211.3 for IPV group; and 1089.5, 538.2, 203.7 for OPV group. IPV showed comparable protection rates with OPV for type 1 and 2 (chi2(I) = 2.991, P = 0.084; chi2(II) = 3.512, P = 0.061), while type 3 was higher than OPV (chi2(III) = 4.143, P = 0.042). The GMT of type 1 and 2 in IPV group were lower than OPV group (Z(I) = 12.537, P = 0.000; Z(II) = 13.415, P = 0.000), while the GMT of type 3 were comparable in two groups (Z(III) = 0.067, P = 0.947). CONCLUSION: IPV showed roughly comparable immunological effectiveness in young children. The protection rates for type 1 and 2 were similar to OPV, while type 3 was higher than in OPV group; In terms of GMT,type 1 and 2 in IPV group were lower than OPV, but type 3 were comparable to OPV group.