Effectiveness of seasonal influenza vaccine in preventing laboratory-confirmed influenza in primary care in the United Kingdom: 2014/15 end of season results

• Published in: Euro surveillance : bulletin européen sur les maladies transmissibles Vol. 20; no. 36; p. 1
• Main Authors: Pebody, Richard, Warburton, Fiona, Andrews, Nick, Ellis, Joanna, von Wissmann, Beatrix, Robertson, Chris, Yonova, Ivelina, Cottrell, Simon, Gallagher, Naomh, Green, Helen, Thompson, Catherine, Galiano, Monica, Marques, Diogo, Gunson, Rory, Reynolds, Arlene, Moore, Catherine, Mullett, David, Pathirannehelage, Sameera, Donati, Matthew, Johnston, Jillian, de Lusignan, Simon, McMenamin, Jim, Zambon, Maria
• Format: Journal Article
• Language: English
• Published: Sweden Centre Europeen pour la Surveillance Epidemiologique du SIDA (European Centre for the Epidemiological Monitoring of AIDS) 10.09.2015
• Subjects: Adolescent; Adult; Aged; Case-Control Studies; Child; Child, Preschool; Effectiveness; Epidemics; Female; Humans; Immunization Programs; Influenza; Influenza A Virus, H3N2 Subtype - genetics; Influenza A Virus, H3N2 Subtype - immunology; Influenza A Virus, H3N2 Subtype - isolation & purification; Influenza B virus - genetics; Influenza B virus - immunology; Influenza B virus - isolation & purification; Influenza Vaccines - administration & dosage; Influenza Vaccines - immunology; Influenza, Human - diagnosis; Influenza, Human - epidemiology; Influenza, Human - prevention & control; Influenza, Human - virology; Laboratories; Male; Middle Aged; Primary care; Primary Health Care; Respiratory Tract Infections - prevention & control; Respiratory Tract Infections - virology; Reverse Transcriptase Polymerase Chain Reaction; Seasons; Sentinel Surveillance; United Kingdom - epidemiology; Vaccination - statistics & numerical data; Vaccines; Young Adult; United Kingdom > UK; influenza; vaccine effectiveness; primary care; UK
• ISSN: 1560-7917; 1025-496X; 1560-7917
• DOI: 10.2807/1560-7917.es.2015.20.36.30013

The 2014/15 influenza season in the United Kingdom (UK) was characterised by circulation of predominantly antigenically and genetically drifted influenza A(H3N2) and B viruses. A universal paediatric influenza vaccination programme using a quadrivalent live attenuated influenza vaccine (LAIV) has recently been introduced in the UK. This study aims to measure the end-of-season influenza vaccine effectiveness (VE), including for LAIV, using the test negative case-control design. The overall adjusted VE against all influenza was 34.3% (95% confidence interval (CI) 17.8 to 47.5); for A(H3N2) 29.3% (95% CI: 8.6 to 45.3) and for B 46.3% (95% CI: 13.9 to 66.5). For those aged under 18 years, influenza A(H3N2) LAIV VE was 35% (95% CI: -29.9 to 67.5), whereas for influenza B the LAIV VE was 100% (95% CI:17.0 to 100.0). Although the VE against influenza A(H3N2) infection was low, there was still evidence of significant protection, together with moderate, significant protection against drifted circulating influenza B viruses. LAIV provided non-significant positive protection against influenza A, with significant protection against B. Further work to assess the population impact of the vaccine programme across the UK is underway.