Safety and immunogenicity of a combined DTacP-sIPV-Hib vaccine in animal models

Nonclinical safety and immunogenicity assessment of a combined DTacP vaccine in animal models

The (diphtheria, tetanus, and pertussis [acellular, component] [DTacP]) vaccine is a combined vaccine designed to prevent three potentially fatal diseases including pertussis, tetanus, and diphtheria in both children and adults. We utilized advanced technology to develop a novel DTacP vaccine that was previously unavailable in China. The nonclinical studies were performed to evaluate the immunogenicity, potential toxicity, and local tolerance of the vaccine in animal models. In the immunogenicity study, three batches of the vaccine were intraperitoneally administered to National Institutes of Health (NIH) mice, resulting in 100% seropositivity for all three batches. Additionally, antibody levels notably increased as the immunization dosage increased. In acute toxicity study, no mortality was observed among the animals during the 14-day observation period, and no abnormalities in clinical signs were reported. Active systemic anaphylaxis assessment in guinea pigs showed no evidence of serious allergic reactions in the vaccine groups. In the repeat-dose toxicity study, where five intramuscular doses were administered every 2 weeks, gross autopsy and histopathological examination revealed no vaccine-related systemic pathological changes in rats, with dose site irritant reactions mostly recovered at the end of recovery period. In conclusion, the vaccine demonstrated good local and systemic tolerance, supporting its clinical development.

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.