Phase III Clinical Trial of Recombinant Respiratory Syncytial Virus Vaccine (CHO Cells)

Inclusion Criteria: (In cases where the required number of participants has not been met, if the criteria described in the "\*" option are not met during screening, the visit can be rescheduled) 1. \*At the time of enrollment, participants must be aged 60 or above, of either gender, and able to provide legal identification; 2. Have the ability to understand the clinical trial procedures, voluntarily agree to participate, and sign the informed consent form; 3. Be able to cooperate and participate in all scheduled follow-ups as required by the protocol; 4. Female trial participants should have undergone menopause or sterilization surgery; \[Menopause is defined as continuous cessation of menstruation for ≥12 months without alternative medical measures; sterilization surgery includes bilateral tubal ligation, bilateral oophorectomy, or hysterectomy\]. 5. Trial participants who are judged by the researchers to have stable health conditions. \[Stable health conditions refer to those with chronic diseases that have been stable for the past 3 months prior to enrollment, such as diabetes, hypertension, chronic obstructive pulmonary disease, and asthma. If the researchers judge the condition to be stable, the participant is allowed to participate in this trial\]. Exclusion Criteria: (If the enrollment requirement is not met, and the criteria described in the "\*" option are met during screening, the visit can be rescheduled) 1. \*On the day before vaccination, the on-site measured temperature is \>37.0℃ (axillary temperature); 2. \*Upon research, the on-site measured blood oxygen saturation (SpO2) is ≤90%; 3. Have previously received or plan to receive any marketed or experimental RSV vaccine/RSV monoclonal antibody; 4. A history of RSV infection confirmed within 6 months prior to enrollment; 5. \*Having used or planning to use any non-specific immunoglobulin and/or blood products containing non-specific immunoglobulin (such as whole blood, plasma) within 3 months before enrollment or during the trial period; 6. \*Have used other investigational or unregistered products (drugs or vaccines) within one month before enrollment, or are currently participating in other clinical trials or plan to participate in other clinical trials during the trial period; 7. \*Having used immunosuppressants or other immunomodulatory drugs for a prolonged period (continuous use ≥14 days) within 3 months before enrollment or during the planned trial period \[such as systemic glucocorticoids for ≥14 days, with a dose ≥2mg/kg/day or ≥20mg/day of prednisone or equivalent to prednisone; however, topical medications (such as ointments, eye drops, inhalers, or nasal sprays) are allowed, and the dose of topical medications must not exceed the recommended dose as stated in the instructions\]; 8. \*Having received a live attenuated vaccine within 30 days before enrollment or planning to receive one within 30 days after enrollment, or having received any non-live vaccine other than the trial vaccine within 14 days before enrollment or planning to receive one within 14 days after enrollment; 9. \*Having an acute disease or being in an acute exacerbation phase of a chronic disease within 3 days before enrollment, or using antipyretic analgesics (excluding medications used to control current diseases and which, in the investigator's judgment, are not expected to affect the interpretation of trial results, such as aspirin used for the treatment of coronary heart disease) or antiallergic medications (e.g., acetaminophen, ibuprofen, aspirin, loratadine, cetirizine, etc.); 10. Individuals with a history of severe allergic reactions requiring medical intervention to any vaccine or medication \[such as anaphylactic shock, allergic laryngeal edema, allergic purpura, thrombocytopenic purpura, local allergic necrotic reaction (Arthus reaction), etc.\] or known allergies to any component of the trial vaccine \[citric acid, sodium citrate, sodium chloride, sucrose, polysorbate 80 (II), mannitol, squalene, sorbitan trioleate (Span 85), water for injection\]; 11. Previous or current congenital or acquired immune deficiency diseases (such as AIDS), human immunodeficiency virus (HIV) infection, systemic lupus erythematosus, or other autoimmune diseases that may affect the trial evaluation as assessed by the investigator (such as a history of inflammatory demyelinating neuropathy like Guillain-Barré syndrome); other diseases affecting immune function (such as asplenia or functional asplenia); 12. Previous or current severe or uncontrollable cardiovascular and cerebrovascular diseases, liver and kidney diseases, respiratory system diseases, diabetes with complications, malignant tumors \[for patients with lacunar cerebral infarction or cerebral infarction without sequelae, or certain malignant tumors (such as papillary thyroid carcinoma, early-stage cervical cancer, basal cell carcinoma, and squamous cell carcinoma of the skin), those who have been stable and relapse-free for 5 years prior to enrollment after careful assessment by the researchers are allowed to be enrolled\]; 13. Currently suffering from or having previously suffered from convulsions, epilepsy (specifically other convulsions and epilepsy other than febrile seizures in children), acute disseminated encephalomyelitis, or other neurological diseases; or having a history of mental illness affecting normal behavior, or a family history of the aforementioned diseases with a genetic predisposition; 14. Suffering from thrombocytopenia, coagulation dysfunction, or any condition that may constitute a contraindication to intramuscular injection; 15. \*Elevated blood pressure (systolic blood pressure ≥160mmHg and/or diastolic blood pressure ≥100mmHg, regardless of medication use) measured through on-site physical examination; 16. Individuals with alcoholism or alcohol dependence (such as an inability to control drinking behavior, and a dependency on alcohol) or drug abuse; 17. Other conditions that researchers consider unsuitable for participation in clinical trials.