1. Clinical Overview
A recombinant, non-infectious, virus-like particle (VLP) vaccine containing purified L1 capsid proteins of Human Papillomavirus (HPV) types 16 and 18. It is adjuvanted with AS04 (aluminum hydroxide and 3-O-desacyl-4'-monophosphoryl lipid A) to enhance and prolong the immune response. It is indicated for the prevention of cervical cancer and other HPV 16/18-related precancerous lesions and diseases.
| Onset | Duration | Bioavailability |
|---|---|---|
| Protective antibody titers are typically achieved within 1 month after the first dose, but the full 3-dose schedule is required for long-term protection. | Long-term follow-up studies show sustained efficacy and immunogenicity for at least 9-10 years post-vaccination. The exact duration of protection is still under study but is expected to be long-lasting. | Not applicable (NA) - Administered via intramuscular injection; systemic bioavailability is 100% for the intended immune response at the injection site. |
2. Mechanism of Action
The vaccine contains recombinant HPV L1 major capsid proteins that self-assemble into non-infectious, non-oncogenic Virus-Like Particles (VLPs) that are morphologically and immunologically identical to the natural virus. Upon intramuscular administration, these VLPs are taken up by antigen-presenting cells (APCs), leading to a robust humoral (B-cell) immune response. The AS04 adjuvant system (Aluminum salt + MPL) enhances the immune response by activating the innate immune system via Toll-like receptor 4 (TLR4), leading to a stronger and more persistent adaptive immune response compared to aluminum salt alone.
3. Indications & Uses
- Prevention of cervical cancer causally related to HPV types 16 and 18.
- Prevention of high-grade cervical intraepithelial neoplasia (CIN 2/3) and adenocarcinoma in situ (AIS) causally related to HPV types 16 and 18.
4. Dosage & Administration
Adult Dosage: Females aged 18-25 years: 0.5 ml intramuscularly, preferably in the deltoid region. Three-dose schedule: Month 0, 1, and 6.
Administration: For intramuscular use only. Shake the vial/pre-filled syringe well before use. Inspect for particulate matter and discoloration. Administer in the deltoid muscle. Do not administer intravenously, intradermally, or subcutaneously. Do not mix with any other vaccine or product in the same syringe.
5. Side Effects
Common side effects may include:
- Pain, redness, and swelling at the injection site.
- Headache, fatigue.
- Myalgia (muscle ache), arthralgia (joint pain).
- Fever (mild, <39°C).
- Gastrointestinal symptoms (nausea, vomiting, diarrhea).
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Immunosuppressants (e.g., corticosteroids, chemotherapy, biologics) | May diminish the immunologic response to the vaccine, leading to suboptimal protection. | Major |
| Other Vaccines | Can be administered concomitantly with other inactivated or live vaccines (e.g., Tdap, Hepatitis B, MenACWY) at separate injection sites. No significant interference in immune response documented. | Minor |
| Anticoagulants (e.g., warfarin) | Increased risk of bleeding or hematoma at injection site. Use a fine needle (23 gauge or smaller) and apply firm pressure for ≥2 minutes. | Moderate |
7. Patient Counselling
- DO complete the full 3-dose schedule for optimal protection.
- DO inform the doctor about any allergies, especially to yeast or previous vaccines.
- DO report if you are pregnant, planning pregnancy, or breastfeeding.
- DONT rub the injection site vigorously after administration.
- DONT take the vaccine if you have a high fever or severe acute illness.
8. Toxicology & Storage
Overdose: There is no experience with overdose. Given the nature of the product (fixed dose in a single-use vial/syringe), overdose is unlikely. If multiple doses were administered, an increase in the frequency and severity of local and systemic adverse reactions would be anticipated.
Storage: Store at +2°C to +8°C (in a refrigerator). Do not freeze. Protect from light. Do not use if the vaccine has been frozen. The vaccine should be administered immediately after withdrawal from the vial. Keep out of reach of children. Use before the expiry date stated on the label.