What is the duration of coverage for Influvac Tetra (quadrivalent influenza vaccine)?

Duration of Protection for Influvac Tetra (Quadrivalent Influenza Vaccine)

Influvac Tetra provides protection for approximately one influenza season, which typically lasts about 6-8 months, and annual revaccination is required.

Understanding Influenza Vaccine Protection Duration

The Advisory Committee on Immunization Practices (ACIP) guidelines do not specify an exact duration of protection for Influvac Tetra specifically, but they provide clear recommendations regarding seasonal influenza vaccination that apply to all influenza vaccines including Influvac Tetra:

• Annual vaccination is recommended because:
  • Immunity from vaccination wanes over time 1
  • Circulating influenza viruses typically change from season to season 1
  • Vaccine composition is updated annually to match circulating strains 1

Factors Affecting Protection Duration

Several factors influence how long protection from Influvac Tetra lasts:

1. Seasonal Virus Changes: Influenza viruses undergo antigenic drift, requiring annual updates to vaccine composition 1

2. Timing of Vaccination:

   • Protection peaks 2-4 weeks after vaccination 2
   • Early vaccination (July/August) may result in reduced protection by the end of the influenza season
   • Ideally, vaccination should be completed by the end of October for optimal protection through the peak of influenza season 1

3. Age and Immune Status:

   • Children and young adults typically develop stronger immune responses than elderly individuals 2
   • Immunocompromised individuals may have shorter duration of protection

Special Population Considerations

Children

• Children aged 6 months through 8 years who have not previously received ≥2 doses of influenza vaccine require 2 doses separated by at least 4 weeks 1
• The two-dose series helps establish adequate immunity in previously unvaccinated or under-vaccinated children 1

Pregnant Women

• Vaccination is recommended at any time during pregnancy 1
• Protection can extend to infants during their first months of life through maternal antibodies 1

Elderly

• While specific data for Influvac Tetra is not provided, it's known that immunity may wane faster in older adults 2

Common Pitfalls to Avoid

1. Assuming Multi-Year Protection: Unlike some vaccines that provide multi-year immunity, influenza vaccines including Influvac Tetra require annual administration due to waning immunity and changing viral strains.

2. Delaying Vaccination: Waiting too long in the season may leave individuals unprotected during early influenza activity.

3. Incorrect Dosing Schedule: For children 6 months through 8 years who have not previously received ≥2 doses of influenza vaccine, failing to administer the second dose will result in suboptimal protection 1.

4. Misinterpreting Vaccine Effectiveness: Vaccine effectiveness varies by season and strain match. Even in years with reduced effectiveness, vaccination can still prevent severe outcomes like hospitalization and death 3.

Conclusion

For optimal protection against seasonal influenza, Influvac Tetra should be administered annually before the start of the influenza season. The protection it provides typically spans one influenza season, and its effectiveness depends on the match between vaccine strains and circulating viruses, as well as individual immune response factors.