What are the alternatives to flu vaccine for individuals with a known allergy to flu vaccines, such as flu block or antiviral medications like oseltamivir (Tamiflu) or zanamivir (Relenza)?

Alternatives to Flu Vaccine for Individuals with Vaccine Allergies

For individuals with allergies to flu vaccines, recombinant influenza vaccine (RIV4, Flublok) is the recommended alternative as it contains no egg protein and has a lower risk of allergic reactions compared to traditional influenza vaccines. 1

Understanding Flu Vaccine Allergies and Alternatives

Recombinant Influenza Vaccine (RIV4)

• First-line alternative: RIV4 (Flublok Quadrivalent) is manufactured without the use of eggs and does not carry a contraindication for egg allergy 1
• Indication: Licensed for adults aged 18 years and older 1
• Advantage: Contains no egg proteins, making it suitable for individuals with egg allergies of any severity 1

Cell-Culture Based Vaccine (ccIIV4)

• Second-line alternative: Flucelvax Quadrivalent (ccIIV4) is prepared using mammalian cell culture rather than eggs 1
• Indication: Licensed for individuals aged 4 years and older 1
• Note: May contain trace amounts of egg proteins as one of the initial viruses is egg-derived, but theoretical maximum is extremely low (1.7×10-8 μg/0.5 mL dose) 1

Decision Algorithm Based on Allergy Type

For Egg Allergy:

1. If history of only hives after egg exposure:

   • Any age-appropriate influenza vaccine (IIV, RIV4, or LAIV4) can be used 1
   • No special precautions needed beyond standard observation

2. If history of reactions beyond hives (angioedema, respiratory distress, lightheadedness, recurrent vomiting):

   • Any age-appropriate influenza vaccine can still be used 1
   • Should be administered in a medical setting with supervision by healthcare providers experienced in recognizing and managing severe allergic reactions
   • RIV4 (Flublok) is preferred if patient is ≥18 years 1

3. If history of severe allergic reaction to previous influenza vaccination:

   • Avoid all influenza vaccines 1
   • Consider antiviral chemoprophylaxis as an alternative 1

Antiviral Medications as Alternatives

When vaccination is contraindicated, antiviral medications can be used for prevention:

Oseltamivir (Tamiflu)

• Dosing for prophylaxis: 75 mg once daily for adults
• Duration: Typically 10 days for post-exposure prophylaxis or longer during community outbreaks 1
• Efficacy: Reduces risk of influenza by >70% when used for seasonal prophylaxis 2
• Side effects: Primarily mild gastrointestinal disturbances 3

Zanamivir (Relenza)

• Dosing for prophylaxis: 10 mg (2 inhalations) once daily 4
• Duration: 10 days for household prophylaxis; up to 28 days for community outbreaks 4
• Contraindication: Not recommended for persons with underlying airways disease due to risk of bronchospasm 4
• Administration: Oral inhalation using DISKHALER device 4

Special Considerations

For Guillain-Barré Syndrome (GBS) History

• If history of GBS within 6 weeks of previous influenza vaccination:
  • Generally should not receive influenza vaccine 1
  • Antiviral chemoprophylaxis is recommended as an alternative 1
  • Exception: Benefits may outweigh risks in those at high risk for severe influenza complications 1

For Children with Allergies

• Children aged 4 years and older can receive ccIIV4 (Flucelvax) 1
• Children with severe allergies to components other than egg proteins should avoid influenza vaccines 1
• Antiviral prophylaxis may be considered for children with contraindications to vaccination 1

Important Caveats

• Antiviral drugs are not a substitute for vaccination but rather an adjunct in specific situations 3
• To avoid resistance development, limit antiviral prophylaxis to situations with high potential benefit 3
• Antiviral prophylaxis should be started within 48 hours after contact with an infected person during an epidemic 3
• If using LAIV4 and antiviral medications, LAIV4 should not be administered until 48 hours after cessation of antiviral therapy 1

Remember that annual vaccination remains the primary strategy for influenza prevention when not contraindicated, and alternatives should only be considered when vaccination is truly not an option due to severe allergic reactions.