2015/16 seasonal vaccine effectiveness against hospitalisation with influenza A(H1N1)pdm09 and B among elderly people in Europe: results from the I-MOVE+ project

We conducted a multicentre test-negative case-control study in 27 hospitals of 11 European countries to measure 2015/16 influenza vaccine effectiveness (IVE) against hospitalised influenza A(H1N1)pdm09 and B among people aged ≥ 65 years. Patients swabbed within 7 days after onset of symptoms compatible with severe acute respiratory infection were included. Information on demographics, vaccination and underlying conditions was collected. Using logistic regression, we measured IVE adjusted for potential confounders. We included 355 influenza A(H1N1)pdm09 cases, 110 influenza B cases, and 1,274 controls. Adjusted IVE against influenza A(H1N1)pdm09 was 42% (95% confidence interval (CI): 22 to 57). It was 59% (95% CI: 23 to 78), 48% (95% CI: 5 to 71), 43% (95% CI: 8 to 65) and 39% (95% CI: 7 to 60) in patients with diabetes mellitus, cancer, lung and heart disease, respectively. Adjusted IVE against influenza B was 52% (95% CI: 24 to 70). It was 62% (95% CI: 5 to 85), 60% (95% CI: 18 to 80) and 36% (95% CI: -23 to 67) in patients with diabetes mellitus, lung and heart disease, respectively. 2015/16 IVE estimates against hospitalised influenza in elderly people was moderate against influenza A(H1N1)pdm09 and B, including among those with diabetes mellitus, cancer, lung or heart diseases.

Description

Members of the I-MOVE+ project - Portugal: Baltazar Nunes, Ana Paula Rodrigues, Raquel Guiomar (Infectious Diseases Department, National Health Institute Doutor Ricardo Jorge, Lisbon, Portugal), Victor Gomes, Filipa Quaresma, Luis Vale, Teresa Garcia, Teresa Bernardo, Liliana Dias, Paula Fonseca, Helena Amorim, João Rolo, Helena Pacheco, Paula Branquinho, Rita Côrte-Real (Centro Hospitalar de Lisboa Central, Lisbon, Portugal),José Poças, Paula Lopes, Maria João Peres, Rosa Ribeiro, Paula Duarte, Ermelinda Pedroso, Sara Rodrigues, Ana Rita Silvério, Diana Gomes Pedreira, Marta Ferreira Fonseca, (Centro Hospitalar de Setúbal, Setúbal, Portugal).

Keywords

Case Control Elderly Influenza Hospitalisation Severe Acute Respiratory Infection Vaccine Effectiveness Vaccine-preventable Diseases Efetividade da Vacina Antigripal Hospital Vacina Antigripal Cuidados de Saúde Infecções Respiratórias