Prevnar 20 - Drug Monograph

Introduction

Prevnar 20 (pneumococcal 20-valent conjugate vaccine) is a vaccine developed by Pfizer that provides active immunization for the prevention of pneumococcal disease caused by Streptococcus pneumoniae serotypes contained in the vaccine. It represents a significant advancement in pneumococcal vaccination, building upon previous conjugate vaccines with expanded serotype coverage.

Mechanism of Action

Prevnar 20 contains polysaccharides from 20 pneumococcal serotypes (1, 3, 4, 5, 6A, 6B, 7F, 8, 9V, 10A, 11A, 12F, 14, 15B, 18C, 19A, 19F, 22F, 23F, and 33F) individually conjugated to diphtheria CRM197 protein. This conjugation converts the T-cell-independent polysaccharide antigens into T-cell-dependent antigens, resulting in enhanced immunogenicity and the induction of immunological memory. The vaccine stimulates B-cells to produce serotype-specific antibodies that facilitate opsonization and phagocytosis of pneumococcal bacteria.

Indications

Prevnar 20 is indicated for:

• Active immunization for the prevention of pneumococcal pneumonia and invasive pneumococcal disease caused by Streptococcus pneumoniae serotypes contained in the vaccine
• Adults 18 years and older
• Pediatric patients 6 weeks through 17 years of age (approved August 2023)

Dosage and Administration

• Single 0.5 mL dose administered intramuscularly
• Preferred injection site: deltoid muscle

• Adults 65+: Single dose regardless of previous pneumococcal vaccination history
• Adults 18-64 with certain risk factors: Consult ACIP guidelines for specific recommendations
• Pediatric patients: Administration schedule varies by age and previous vaccination history

• Do not administer intravenously, subcutaneously, or intradermally
• Shake well before administration
• Do not mix with other vaccines in same syringe

Pharmacokinetics

As a vaccine, Prevnar 20 does not follow traditional pharmacokinetic parameters. The immune response typically begins within 2-3 weeks post-vaccination, with peak antibody levels reached within 4-6 weeks. The CRM197 carrier protein is metabolized through normal protein catabolic pathways. Immune memory persists for years, though duration of protection may vary by serotype and individual patient factors.

Contraindications

• Severe allergic reaction (e.g., anaphylaxis) to any component of Prevnar 20
• History of severe allergic reaction to any diphtheria toxoid-containing vaccine

Warnings and Precautions

• Syncope may occur following vaccination
• Apnea in premature infants; consider respiratory monitoring for 48 hours
• Altered immunocompetence may result in reduced immune response
• Guillain-Barré syndrome has been reported rarely following pneumococcal conjugate vaccination
• Not all pneumococcal serotypes are covered by the vaccine

Drug Interactions

• Immunosuppressive therapies: May diminish immune response
• Anticoagulant therapy: Increased risk of bleeding/hematoma at injection site
• Other vaccines: May be administered simultaneously at different injection sites
• Previous pneumococcal vaccination: Timing considerations apply; consult CDC/ACIP guidelines

Adverse Effects

• Injection site pain (75.5%)
• Fatigue (30.5%)
• Headache (25.5%)
• Myalgia (22.5%)
• Injection site swelling (21.0%)
• Arthralgia (13.5%)
• Injection site redness (11.0%)

• Anaphylaxis (<1 per million doses)
• Febrile seizures (rare)
• Guillain-Barré syndrome (rare)

Monitoring Parameters

• Local injection site reactions for 2-3 days post-vaccination
• Temperature for febrile reactions
• Signs of hypersensitivity reactions
• Documentation of vaccination in medical records and immunization registries

Patient Education

• Expect mild to moderate injection site discomfort lasting 1-2 days
• Use analgesic/antipyretic medications if needed for symptoms
• Seek medical attention for signs of severe allergic reaction (hives, swelling, difficulty breathing)
• This vaccine does not protect against all pneumococcal serotypes
• Continue following recommended preventive health measures
• Keep vaccination record for future reference

References

1. Prevnar 20 Prescribing Information. Pfizer Inc. 2023. 2. Centers for Disease Control and Prevention. Pneumococcal Vaccine Recommendations. ACIP Guidelines, 2023. 3. Essink B, et al. Phase 3 Trial of 20-Valent Pneumococcal Conjugate Vaccine in Adults. NEJM. 2021;385:1559-1573. 4. Food and Drug Administration. Prevnar 20 Approval Letter. June 2021. 5. American Academy of Pediatrics. Red Book: 2021-2024 Report of the Committee on Infectious Diseases. 6. Kobayashi M, et al. Intervals Between PCV13 and PPSV23 Vaccines: Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR. 2015;64(34):944-947.