488. Influenza vaccine effectiveness in preventing admissions with influenza during the 2014-2015 influenza season. A test-negative hospital-based study, in the Valencia Hospital Network for the Study of Influenza and Respiratory Viruses Disease, Valencia (Spain)
Session: Poster Abstract Session: Respiratory Infections: Influenza
Thursday, October 8, 2015
Room: Poster Hall
Posters
  • IDWeek 488 VAHNSI IVE 2014_15 @ Poster.ppt.pdf (1.0 MB)
  • Background:

    The 2014/15 influenza season was characterised by the circulation of A(H3N2)  viruses belonging to clade 3C.2a and 3C.3a, distinct from the A/Texas/50/2012(H3N2)-like (clade 3C.1) reference for the 2014/15 vaccine. In addition, B Yamagata lineage and few A(H1N1)pdm09 were identified. Preliminary influenza vaccine effectiveness (IVE) estimates in Europe and North America reported null to low IVE against confirmed influenza acute respiratory infection.

    Methods:

    We performed a test-negative study in ten hospitals that provided care to 2,351,526 inhabitants. We enrolled consecutive consenting admissions of non-institutionalized, 18 years old or older subjects, with onset of influenza-like-illness (ILI) within 7 days of hospitalization. We obtained combined nasopharyngeal swabs and influenza was confirmed by RT–PCR. A split trivalent vaccine (Vaxigrip®; SANOFI PASTEUR MSD) was offered free of charge to subjects targeted for influenza vaccination. We considered a subject as immunized when vaccinated 15 or more days before ILI onset. We estimated IVE as (1-odds ratio)*100, taking into account clustering by hospital and epidemiological week.

    Results:

    We enrolled 2,713 admissions, 653 influenza positive (546 (84%), A(H3N2); 56 (9%) B Yamagata; 38 (6%) A no subtyped; 9 (1%) A(H1N1)pdm09 and 4 (0.6%) B with no lineage) and 2060 influenza negative; 87 (19.5%) <65 years old were influenza positive compared to 566 (25.0%) >=65 years old; 1334 (65%) influenza negative were vaccinated compared to 383 (59%) influenza positive; 158 (35%)  <65 years old were vaccinated compared to 1,559 (69%) >=65 years old.

    For subjects over 18 years of age, overall adjusted IVE was 18% (-1 to 34%) and 50% (13% to 71%) in preventing A(H3N2) or influenza B admissions, respectively. When considering subjects 65 years old or older, adjusted IVE was 32% (15% to 46%); 30% (12% to 45%) and 60% (27% to 78%) in preventing admissions with influenza, influenza A(H3N2) or influenza B, respectively.

    Conclusion:

    The vaccine conferred moderate protection against the risk of admission with influenza. Low effectiveness against A(H3N2) was most possibly due to mismatch, whereas, vaccination more than halved admissions with influenza B.

    Joan Puig-Barberà, MD, MPH, PhD1,2, Ainara Mira-Iglesias, MSc.1, Miguel Tortajada-Girbés, MD3, F. Xavier López-Labrador, PhD1,4, Ángel Belenguer-Varea, MD5, Mario Carballido-Fernández, MD6, Empar Carbonell-Franco, MD7, Concha Carratalà-Munuera, MD. , PhD8,9, Ramón Limón-Ramírez, MD10, Joan Mollar-Maseres, MD11, Maria Del Carmen Otero-Reigada, MD11, Germán Schwarz-Chavarri, MD12, José Tuells-Hernández, MD13 and Vicente Gil-Guillén, MD. , PhD9,14, (1)Fundación para el Fomento de la investigación Sanitaria y Biomédica de la Comunidad Valenciana (FISABIO), Valencia, Spain, (2)Centro de Salud Pública de Castellón, Castellón, Spain, (3)Hospital Universitario Doctor Peset, Valencia, Spain, (4)Consorcio de Investigación Biomédica de Epidemiología y Salud Pública (CIBERESP), Instituto de Salud Carlos III, Madrid, Spain, (5)Hospital Universitario de La Ribera, Valencia, Spain, (6)Hospital General de Castellón, Castellón, Spain, (7)Hospital Arnau de Vilanova, Valencia, Spain, (8)Hospital San Juan, Alicante, Spain, (9)Departamento De Medicina Clínica, Cátedra De Medicina De Familia.Universidad Miguel Hernández, Alicante, Spain, (10)Hospital de la Plana, Castellón, Spain, (11)Hospital Universitario y Politécnico La Fe, Valencia, Spain, (12)Hospital General de Alicante, Alicante, Spain, (13)Hospital Universitario del Vinalopó, Alicante, Spain, (14)Hospital de Elda, Alicante, Spain

    Disclosures:

    J. Puig-Barberà, Sanofi Pasteur Institution: funding for the study , Research support

    A. Mira-Iglesias, Sanofi Pasteur Institution: funding for the study , Research support

    M. Tortajada-Girbés, Sanofi Pasteur Institution: funding for the study , Research support

    F. X. López-Labrador, Sanofi Pasteur Institution: funding for the study , Research support

    Belenguer-Varea, Sanofi Pasteur Institution: funding for the study , Research support

    M. Carballido-Fernández, Sanofi Pasteur Institution: funding for the study , Research support

    E. Carbonell-Franco, Sanofi Pasteur Institution: funding for the study , Research support

    C. Carratalà-Munuera, Sanofi Pasteur Institution: funding for the study , Research support

    R. Limón-Ramírez, Sanofi Pasteur Institution: funding for the study , Research support

    J. Mollar-Maseres, Sanofi Pasteur Institution: funding for the study , Research support

    M. D. C. Otero-Reigada, Sanofi Pasteur Institution: funding for the study , Research support

    G. Schwarz-Chavarri, Sanofi Pasteur Institution: funding for the study , Research support

    J. Tuells-Hernández, Sanofi Pasteur Institution: funding for the study , Research support

    V. Gil-Guillén, Sanofi Pasteur Institution: funding for the study , Research support

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