A Study to Evaluate the Safety and Immunogenicity of VLP-Polio in Infants and Toddlers

Inclusion Criteria:

• Healthy toddlers aged 12-18 months at the time of screening, and have completedprimary immunization of polio vaccine according to the national government programin the first year of life.

• Healthy infants aged 6 weeks to 2 months (42 to 98 days, with the day of birthconsidered day of life 1), and who have not received any polio vaccines.

• Able to obtain written informed consent from parent(s) or legal guardian(s).

• Participants and their parents or legal guardian(s) can comply with trialprocedures, are available for the duration of follow-up, and have a suitabletelephone contact available.

Exclusion Criteria:

Exclusion criteria for the first dose:

• Current polio disease or history of polio disease.

• Toddlers who have an interval of less than 5 months since their last dose of thepolio vaccine.

• Infants born at < 37 weeks of gestation.

• Children with a birth weight < 2500g and a body weight < 3500g at the time ofenrollment.

• Body temperature ≥37.5°C (the visit may be rescheduled when this criterion is met).

• Have congenital malformations or developmental disorders, genetic defects, severemalnutrition, etc.

• Any moderate or severe acute illness.

• Any abnormal vital signs.

• History of epilepsy, convulsions, or parent with congenital cognitive disability,dementia, or intellectual disabilities.

• Have received immunosuppressive treatment, cytotoxic treatment, glucocorticoidtreatment, etc. (excluding local treatment, surface treatment of acutenon-concurrent dermatitis, or spray treatment of allergic rhinitis).

• Received or plan to receive blood/plasma products or immunoglobulins throughout thestudy period or prior to study vaccination.

• History of serious adverse events and/or severe allergic reactions (e.g., systemicallergic reactions) to any component of the study vaccine.

• History of known disturbance of coagulation or blood disorder that could causeanemia or excess bleeding (e.g., thalassemia, coagulation factor deficiencies,severe anemia at birth).

• Immunocompromised individuals with known or suspected immunodeficiency as determinedby medical history and/or physical examination (e.g., history of pancreatic, liver,spleen, kidney disease or history of resection).

• Administration of other vaccines within 7 days.

• Participation in other interventional studies within 28 days prior to screeningand/or during study participation.

• Household member or sibling who has received or is scheduled to receive OPV in theprevious 3 months until 5 weeks after the third dose of the primary immunizationseries.

• The participant is a direct descendant (child or grandchild) of any person employedby the Sponsor, the contract research organization (CRO), the investigator, or studysite personnel.

• History or current evidence of any condition or therapy which might confound theresults of the study, interfere with the participant's participation for the fullduration of the study, indicate suspected diseases, or is not in the best interestof the participants to participate, in the opinion of the treating investigator.

• Family history of any medical conditions, that in the investigating doctor'sopinion, could affect the trial outcomes.

• Any reason or condition the investigator considers sufficient to make a participantineligible for participation in the study.

Exclusion criteria for the subsequent doses:

• Severe allergic reaction after the previous vaccination.

• Serious adverse events caused by the previous vaccination.

• Newly identified symptoms or newly occurred cases after the first vaccination thatdo not meet the inclusion criteria for the first dose, or that meet the exclusioncriteria for the first dose. The decision to discontinue participation is determinedby the investigator.

• Other reasons for exclusion considered by the investigating doctor .