Implementing an Influenza Vaccine Effectiveness Study in a Hospital Context in Portugal: The EVA Hospital Project ; Implementação de um Estudo de Efetividade da Vacina Contra a Gripe no Contexto Hospitalar em Portugal: Projeto EVA Hospital
EVA Hospital Group: Irina Kislaya, Ana Paula Rodrigues, Liliana Dias, Paula Branquinho, Cláudia Mihon, Ana Rita Estriga, Ana Brito, Luís Vale, Helena Pacheco, André Almeida, Helena Amorim, Paula Lopes, Vitor Augusto, Rosa Ribeiro, Regina Viseu, Raquel Guiomar, Pedro Pechirra, Paula Cristovão, Patrícia Conde. ; Erratum in: Acta Med Port. 2021 Jan 4;34(1):70-73. doi:10.20344/amp.15515. Epub 2021 Jan 4. ; Introduction: The project 'Integrated Monitoring of Vaccines in Europe' aimed to measure seasonal influenza vaccine effectiveness against hospitalised adults, aged 65 years and over, with influenza. We describe the protocol implementation in Portugal. Material and Methods: We implemented a test-negative design, targeting community-dwelling patients aged 65 years old and over hospitalised with severe acute respiratory illness. Patients were reverse transverse-polymerase chain reaction tested for influenza. Cases were those positive for influenza while others were controls. Most variables were collected using hospital medical records. Selection bias was evaluated by comparison with the laboratory influenza test requests database according to demographic characteristics. Crude, season-adjusted influenza vaccine effectiveness was estimated as = 1 – odds ratio, and 95% confidence intervals were obtained by conditional logistical regression, matched with the disease onset month. Results: The recruitment rate was 37.8%. Most participants (n = 368) were female (55.8%) and aged 80 years old and over (55.8%). This was similar to values for potentially eligible severe acute respiratory illness patients (80 years old and over: 56.8%, female: 56.2%). The proportion of missing values was below 2.5% for 20 variables and above 5% (maximum 11.6%) for six variables. Influenza vaccine effectiveness estimates were 62.1% against AH1pdm09 (95% confidence intervals: -28.1 to 88.8), 14.9% against A(H3N2) (95% confidence intervals: -69.6 to 57.3), 43.6% against B/Yam (95% confidence intervals: -66.2 to 80.8). Discussion: Given the non-existence of a coded admission database in either participating hospital the selection of severe acute respiratory illness due to clinical features was the feasible one. These results are only valid for the older adult population residing in the catchment area of the two participating hospitals who were admitted to a public hospital with severe influenza or SARI symptoms. Conclusion: Despite the low participation rate, we observed comparable characteristics of participants and eligible severe acute respiratory illness patients. Data quality was high, and influenza vaccine effectiveness results were in accordance with the results of meta-analyses and European season-specific estimates. The final sample size was low, which inhibited obtaining estimates with good precision. ; Introdução: O projeto "Integrated Monitoring of Vaccines in Europe" pretende medir a efetividade da vacina antigripal nas hospitalizações por gripe nos adultos com mais de 65 anos. Este estudo pretende descrever a implementação do protocolo em Portugal. Material e Métodos: Implementou-se um estudo com desenho caso-controlo teste negativo. A população-alvo foram indivíduos com idade superior a 65 anos, hospitalizados com doença respiratória aguda grave. Os doentes foram testados para gripe por reverse transverse-polimerase chain reaction. Foram considerados casos aqueles com resultado positivo; os restantes foram controlos. Os dados foram obtidos através de registo clinicos. O potencial viés de seleção foi avaliado por comparação de características demográficas e enfermarias com dados das requisições laboratoriais. A efetividade da vacina, foi estimada em 1 – odds ratio por regressão logística condicional, emparelhada para o mês de início da doença. Resultados: A taxa de recrutamento foi de 37,8%. A maioria dos participantes (n = 368) era do sexo feminino (55,8%) e tinha idade superior a 80 anos (55,8%). Padrão similar foi verificado nos doentes elegíveis (idade superior a 80 anos: 56,8%; feminino: 56,2%). Os valores omissos foram inferiores a 2,5% em 20 variáveis e acima de 5% (máximo 11,6%) em seis variáveis. As estimativas da efetividade foram 62,1% contra AH1pdm09 (intervalo de confiança IC 95%: -28,1, 88,8); 14,9% contra A (H3) (intervalo de confiança 95%: -69,6; 57,3) e 43,6% contra B/yamagata (intervalo de confiança 95%: -66,2; 80,8). ; Abstract in English, Portuguese ; This work is part of I-MOVE+ (Integrated Monitoring of Vaccines in Europe) project that received funding from the European Union's Horizon 2020 research and innovation programme [grant agreement number 634446]. ; info:eu-repo/semantics/publishedVersion