To provide a basis for further optimization of the polio sequential immunization schedule, this study evaluated the effectiveness of booster immunization with one dose of bivalent oral poliovirus vaccine (bOPV) at 48 months of age after different primary polio immunization schedules. At 48 months of age, one dose of bOPV was administered, and their poliovirus types 1–3 (PV1, PV2, and PV3, respectively)-specific neutralizing antibody levels were determined. Participants found to be negative for any type of PV-specific neutralizing antibody at 24, 36, or 48 months of age were re-vaccinated with inactivated polio vaccine (IPV). The 439 subjects who received a bOPV booster immunization at the age of 48 months had lower PV2-specific antibody levels compared with those who received IPV. One dose of IPV during basic polio immunization induced the lowest PV2-specific antibody levels. On the basis of our findings, to ensure that no less than 70% of the vaccinated have protection efficiency, we recommend the following: if basic immunization was conducted with 1IPV + 2bOPV (especially Sabin strain-based IPV), a booster immunization with IPV is recommended at 36 months of age, whereas if basic immunization was conducted with 2IPV + 1bOPV, a booster immunization with IPV is recommended at 48 months of age. A sequential immunization schedule of 2IPV + 1bOPV + 1IPV can not only maintain high levels of antibody against PV1 and PV3 but also increases immunity to PV2 and induces early intestinal mucosal immunity, with relatively good safety. Thus, this may be the best sequential immunization schedule for polio in countries or regions at high risk for polio.

为进一步优化脊髓灰质炎序贯免疫计划提供依据，本研究评估了在不同初级脊髓灰质炎免疫计划后，在 48 月龄时使用一剂双价口服脊髓灰质炎病毒疫苗 (bOPV) 加强免疫的有效性。在 48 个月大时，接种了一剂 bOPV，并测定了他们的 1-3 型脊髓灰质炎病毒（分别为 PV1、PV2 和 PV3）特异性中和抗体水平。在 24、36 或 48 个月大时被发现对任何类型的 PV 特异性中和抗体呈阴性的参与者重新接种了灭活脊髓灰质炎疫苗 (IPV)。与接受 IPV 的受试者相比，在 48 个月大时接受 bOPV 加强免疫的 439 名受试者的 PV2 特异性抗体水平较低。在基础脊髓灰质炎免疫接种期间接种一剂 IPV 可诱导最低的 PV2 特异性抗体水平。根据我们的研究结果，为确保不少于 70% 的接种者具有保护效率，我们建议如下：如果使用 1IPV + 2bOPV（尤其是基于 Sabin 株的 IPV）进行基础免疫，则使用 IPV 进行加强免疫建议在 36 月龄时进行，而如果使用 2IPV + 1bOPV 进行基础免疫，则建议在 48 月龄时进行 IPV 加强免疫。2IPV+1bOPV+1IPV序贯免疫方案，既能维持高水平的PV1、PV3抗体，又能增加PV2免疫，诱导早期肠黏膜免疫，安全性较好。因此，