A Study to Evaluate the Immune Response Features Following Vaccination With a Recombinant Respiratory Syncytial Virus Vaccine (CHO Cells)

Inclusion Criteria: * Participants must be 20 years of age or older as determined by the investigator at enrollment. * Participants must be able to understand study procedures, risks, and benefits, provide voluntary agreement to participate in the study, and sign the informed consent form (ICF). * Participants must be willing and able to attend all scheduled follow-up visits and comply with all requirements specified in the study protocol. * Females of childbearing potential must use highly effective contraception from 1 month prior to vaccination through 12 months following vaccination. * Effective contraceptive methods include: oral contraceptives (excluding emergency contraceptives), contraceptive injections, subcutaneous implants, hormonal patches, intrauterine devices (IUDs), surgical sterilization, true abstinence, and condom use. * Methods not considered effective include: rhythm method, withdrawal method, and emergency contraception. Exclusion Criteria: \*Participants who meet any of the following criteria shall be ineligible for enrollment: * Axillary body temperature ≥ 37.3 °C. * History of respiratory syncytial virus (RSV) infection within 6 months prior to enrollment. * New-onset respiratory infection symptoms within 7 days prior to enrollment, including cough, expectoration, dyspnea, wheezing, fever, rhinorrhea, and nasal obstruction. * Presence of an acute illness or acute exacerbation of a chronic condition within 3 days prior to enrollment. * Use of a…