Clinical Study on Immunogenicity and Safety of Lyophilized Vero Cell-Derived Human Rabies Vaccine in Special Populations

This is a controlled study consisting of a study group and a control group. The study group will include special population participants (non-HIV-related immunocompromised individuals, patients with chronic diseases, and elderly individuals) who are receiving their first clinical visit after confirmed WHO category II or III rabies exposure. The control group will include healthy adults aged 18 to under 60 years who also present after similar exposure. The study group will be further divided into three subgroups based on the health status of the participants, with 50 individuals in each subgroup:

• Immunocompromised group: including individuals with primary immunodeficiency diseases, hematologic or solid organ malignancies, aplastic anemia, and autoimmune diseases under long-term immunosuppressive therapy;
• Chronic disease group: including patients with diabetes, chronic hepatitis, cirrhosis, chronic glomerulonephritis, nephrotic syndrome, and chronic renal insufficiency;
• Elderly group: participants aged 60 years and above (including those aged exactly 60).

If a participant meets criteria for more than one subgroup (e.g., aged ≥60 years and also has immunodeficiency or a chronic disease), subgroup assignment will be prioritized based on disease condition: immunocompromised first, then chronic disease, and finally elderly, to ensure each participant is assigned to the most representative subgroup.

All participants (both in the study and control groups) may choose either the Zagreb regimen (2-1-1) or the Essen regimen (five-dose schedule) for post-exposure rabies vaccination. Adverse events occurring within 0-7 days after each vaccine dose will be collected via telephone follow-up to understand post-vaccination responses.

Blood samples will be collected at Day 14 after completion of the full vaccination schedule (i.e., Day 35 from first dose for Zagreb regimen and Day 42 for Essen regimen), and again at Day 90 (Day 111 and Day 118 from first dose for Zagreb and Essen, respectively). Rabies virus neutralizing antibodies will be tested and compared between groups to evaluate the immunogenicity of rabies vaccination in special populations after exposure. Safety data will also be analyzed and compared between groups.

Inclusion criteria

• Subjects with WHO category II or III rabies exposure presenting at the study site for post-exposure prophylaxis and vaccination.
• Subjects planned to be included in the control group, aged 18 to less than 60 years old, healthy as confirmed by medical history, physical examination, and clinical judgment before vaccination.
• Subjects planned to be included in the study group who meet any of the following conditions:

• Long-term immunocompromised status due to conditions including, but not limited to: clinically confirmed primary immunodeficiency diseases; hematologic or solid organ malignancies; aplastic anemia; clinically confirmed autoimmune diseases with immunosuppressive therapy lasting 4 weeks or longer within the past 12 months prior to enrollment; history of splenectomy or other major immunologic organ removal; hematopoietic stem cell or solid organ transplantation within 2 years prior to enrollment.
• Clinically confirmed diabetes mellitus, chronic hepatitis, liver cirrhosis, chronic glomerulonephritis, nephrotic syndrome, or chronic renal insufficiency.
• Age 60 years or older.
• Subjects or their legally authorized representatives are able to understand the study requirements and procedures, voluntarily agree to participate, and sign the informed consent form.
• Subjects are able to comply with all planned follow-up visits and provide valid identification documents of themselves and/or their legally authorized representatives.

Exclusion criteria

• History of previous rabies vaccination.
• History of human immunodeficiency virus (HIV) infection.
• Other conditions deemed unsuitable for participation in the clinical study by the investigator.