Retrospective public health impact of a quadrivalent influenza vaccine in the United States

• Published in: Influenza and other respiratory viruses 2015-08, Vol.9 (S1), p.39-46
• Main Authors: Crépey, Pascal, Boer, Pieter T., Postma, Maarten J., Pitman, Richard
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Age; Age Factors; Aged; Aged, 80 and over; Analysis; Child; Child, Preschool; Computer simulation; Cross Protection; Disease control; Disease prevention; Dynamic model; Epidemics; Female; Geriatrics; Health aspects; Health insurance; Human health and pathology; Humans; Immunity; Immunology; Infant; Infant, Newborn; Infections; Infectious diseases; Influenza; Influenza B; Influenza B virus - genetics; Influenza B virus - immunology; Influenza vaccines; Influenza Vaccines - administration & dosage; Influenza Vaccines - chemistry; Influenza, Human - epidemiology; Influenza, Human - prevention & control; Licensure; Life Sciences; Male; Medical research; Medicine, Experimental; Middle Aged; Models, Immunological; Original; Population; Population biology; Public Health; quadrivalent influenza vaccine; Respiratory diseases; Retrospective Studies; Santé publique et épidémiologie; Sensitivity analysis; Studies; Time Factors; Time series; trivalent influenza vaccine; United States - epidemiology; Vaccination; vaccine effectiveness; Vaccine efficacy; Vaccines; Vaccinology; Viruses; Young Adult
• ISSN: 1750-2640; 1750-2659
• DOI: 10.1111/irv.12318

Introduction Vaccination is an effective preventive strategy against influenza. However, current trivalent influenza vaccines (TIVs) contain only one of the two influenza B lineages that circulate each year. Vaccine mismatches are frequent because predicting which one will predominate is difficult. Recently licensed quadrivalent influenza vaccines (QIVs) containing the two B lineages should address this issue. Our study estimates their impact by assessing what would have been the US public health benefit of routinely vaccinating with QIV in 2000–2013. Methods We developed a dynamic compartmental model that accounts for interactions between influenza B lineages (natural or vaccine‐induced) and simulates the multiyear influenza dynamics for 2000–2013. Age‐structured population dynamics, vaccine efficacy (VE) per strain, and weekly ramp‐up of vaccination coverage are modeled. Sensitivity analyses were performed on VE, duration of immunity, and levels of vaccine‐induced cross‐protection between B lineages. Results Assuming a cross‐protection of 70% of the VE of the matched vaccine, the model predicts 16% more B lineage cases prevented by QIV. Elderly (≥65 years) and young seniors (50–64 years) benefit most from QIV, with 21% and 18% reductions in B lineage cases. Reducing cross‐protection to 50%, 30%, and 0% of the VE of the matched vaccine improves the relative benefit of QIV to 25%, 30%, and 34% less B lineage cases. Conclusion Using a dynamic retrospective framework with real‐life vaccine mismatch, our analysis shows that QIV routine vaccination in the United States has the potential to substantially reduce the number of influenza infections, even with relatively high estimates of TIV‐induced cross‐protection.