Immunogenicity of Catch-Up Immunization with Conventional Inactivated Polio Vaccine among Japanese Adults

Observational analysis of the immunogenicity and safety of various types of spinal muscular atrophy vaccines

BACKGROUND

This study aimed to evaluate the immunogenicity and safety of different types of poliovirus vaccines.

METHODS

A randomized, blinded, single-center, parallel-controlled design was employed, and 360 infants aged ≥ 2 months were selected as study subjects. They were randomly assigned to bOPV group (oral Sabin vaccine) and sIPV group (Sabin strain inactivated polio vaccine), with 180 infants in each group. Adverse reaction events in the vaccinated subjects were recorded. The micro-neutralization test using cell culture was conducted to determine the geometric mean titer (GMT) of neutralizing antibodies against poliovirus types I, II, and III in different groups, and the seroconversion rates were calculated.

RESULTS

Both groups exhibited a 100% seropositivity rate after booster immunization. The titers of neutralizing antibodies for the three types were predominantly distributed within the range of 1:128 to 1:512. The fold increase of type I antibodies differed markedly between the two groups (P < 0.05). Moreover, the fold increase of type II and type III antibodies for poliovirus differed slightly between the two groups (P > 0.05). The fourfold increase rate in sIPV group was drastically superior to that in bOPV group (P < 0.05). When comparing the post-immunization GMT levels of type I antibodies in individuals who completed the full course of spinal muscular atrophy vaccination, bOPV group showed greatly inferior levels to sIPV group (P < 0.05). For type II and type III antibodies, individuals in bOPV group demonstrated drastically superior post-immunization GMT levels to those in sIPV group (P < 0.05). The incidence of adverse reactions between the bOPV and sIPV groups differed slightly (P > 0.05).

CONCLUSION

These findings indicated that both the oral vaccine and inactivated vaccine had good safety and immunogenicity in infants aged ≥ 2 months. The sIPV group generated higher levels of neutralizing antibodies in serum, particularly evident in the post-immunization GMT levels for types II and III.

Use of Inactivated Polio Vaccine Among U.S. Adults: Updated Recommendations of the Advisory Committee on Immunization Practices - United States, 2023

Poliovirus can cause poliomyelitis and lifelong paralysis. Although wild poliovirus types 2 and 3 have been eradicated, wild poliovirus type 1 and vaccine-derived polioviruses are still circulating in multiple countries worldwide. In 2022, a case of paralytic polio caused by vaccine-derived poliovirus type 2 was identified in an unvaccinated young adult in New York. This case and subsequent detection of community transmission underscored the ongoing risk for importation of poliovirus into the United States and risk for poliomyelitis among unvaccinated persons. However, previous Advisory Committee on Immunization Practices (ACIP) recommendations for adult polio vaccination were limited to adults known to be at increased risk for exposure. During October 2022-June 2023, the ACIP Polio Vaccine Work Group reviewed data on poliovirus surveillance and epidemiology, safety and effectiveness of inactivated poliovirus vaccine (IPV), and other considerations outlined in the ACIP Evidence to Recommendations Framework. On June 21, 2023, ACIP voted to recommend that all U.S. adults aged ≥18 years who are known or suspected to be unvaccinated or incompletely vaccinated against polio complete a primary polio vaccination series with IPV. This report summarizes evidence considered for this recommendation and provides clinical guidance for the use of IPV in adults.