BACKGROUND: The effectiveness of influenza vaccination against hospitalization and death can only ethically be assessed in observational studies. A concern is that individuals who are vaccinated are healthier than individuals who are not vaccinated, potentially biasing estimates of effectiveness upward. METHODS: We conducted a historical cohort study of individuals >64 years of age, for whom there were data available in the General Practice Research Database for 1989 to 1999 in England and Wales. Rates of admissions for acute respiratory diseases and rates of death due to respiratory disease were compared over 692,819 person-years in vaccine recipients and 1,534,280 person-years in vaccine nonrecipients. RESULTS: The pooled effectiveness of vaccine against hospitalizations for acute respiratory disease was 21% (95% confidence interval [CI], 17%-26%). The rate reduction attributable to vaccination was 4.15 hospitalizations/100,000 person-weeks in the influenza season. Among vaccine recipients, no important reduction in the number of admissions to the hospital was seen outside influenza seasons. The pooled effectiveness of vaccine against deaths due to respiratory disease was 12% (95% CI, 8%-16%). A greater proportionate reduction was seen among people without medical disorders, but absolute rate reduction was higher in individuals with medical disorders, compared with individuals without such disorders (6.14 deaths due to respiratory disease/100,000 person-weeks vs. 3.12 deaths due to respiratory disease/100,000 person-weeks). Clear protection against death due to all causes was not seen. CONCLUSIONS: Influenza vaccination reduces the number of hospitalizations and deaths due to respiratory disease, after correction for confounding in individuals >64 years of age who had a high risk or a low risk for influenza. For elderly people, untargeted influenza vaccination is of confirmed benefit against serious outcomes.
BACKGROUND: The effectiveness of influenza vaccination against hospitalization and death can only ethically be assessed in observational studies. A concern is that individuals who are vaccinated are healthier than individuals who are not vaccinated, potentially biasing estimates of effectiveness upward. METHODS: We conducted a historical cohort study of individuals >64 years of age, for whom there were data available in the General Practice Research Database for 1989 to 1999 in England and Wales. Rates of admissions for acute respiratory diseases and rates of death due to respiratory disease were compared over 692,819 person-years in vaccine recipients and 1,534,280 person-years in vaccine nonrecipients. RESULTS: The pooled effectiveness of vaccine against hospitalizations for acute respiratory disease was 21% (95% confidence interval [CI], 17%-26%). The rate reduction attributable to vaccination was 4.15 hospitalizations/100,000 person-weeks in the influenza season. Among vaccine recipients, no important reduction in the number of admissions to the hospital was seen outside influenza seasons. The pooled effectiveness of vaccine against deaths due to respiratory disease was 12% (95% CI, 8%-16%). A greater proportionate reduction was seen among people without medical disorders, but absolute rate reduction was higher in individuals with medical disorders, compared with individuals without such disorders (6.14 deaths due to respiratory disease/100,000 person-weeks vs. 3.12 deaths due to respiratory disease/100,000 person-weeks). Clear protection against death due to all causes was not seen. CONCLUSIONS: Influenza vaccination reduces the number of hospitalizations and deaths due to respiratory disease, after correction for confounding in individuals >64 years of age who had a high risk or a low risk for influenza. For elderly people, untargeted influenza vaccination is of confirmed benefit against serious outcomes.
Authors: Dalton Bertolim Précoma; Gláucia Maria Moraes de Oliveira; Antonio Felipe Simão; Oscar Pereira Dutra; Otávio Rizzi Coelho; Maria Cristina de Oliveira Izar; Rui Manuel Dos Santos Póvoa; Isabela de Carlos Back Giuliano; Aristóteles Comte de Alencar Filho; Carlos Alberto Machado; Carlos Scherr; Francisco Antonio Helfenstein Fonseca; Raul Dias Dos Santos Filho; Tales de Carvalho; Álvaro Avezum; Roberto Esporcatte; Bruno Ramos Nascimento; David de Pádua Brasil; Gabriel Porto Soares; Paolo Blanco Villela; Roberto Muniz Ferreira; Wolney de Andrade Martins; Andrei C Sposito; Bruno Halpern; José Francisco Kerr Saraiva; Luiz Sergio Fernandes Carvalho; Marcos Antônio Tambascia; Otávio Rizzi Coelho-Filho; Adriana Bertolami; Harry Correa Filho; Hermes Toros Xavier; José Rocha Faria-Neto; Marcelo Chiara Bertolami; Viviane Zorzanelli Rocha Giraldez; Andrea Araújo Brandão; Audes Diógenes de Magalhães Feitosa; Celso Amodeo; Dilma do Socorro Moraes de Souza; Eduardo Costa Duarte Barbosa; Marcus Vinícius Bolívar Malachias; Weimar Kunz Sebba Barroso de Souza; Fernando Augusto Alves da Costa; Ivan Romero Rivera; Lucia Campos Pellanda; Maria Alayde Mendonça da Silva; Aloyzio Cechella Achutti; André Ribeiro Langowiski; Carla Janice Baister Lantieri; Jaqueline Ribeiro Scholz; Silvia Maria Cury Ismael; José Carlos Aidar Ayoub; Luiz César Nazário Scala; Mario Fritsch Neves; Paulo Cesar Brandão Veiga Jardim; Sandra Cristina Pereira Costa Fuchs; Thiago de Souza Veiga Jardim; Emilio Hideyuki Moriguchi; Jamil Cherem Schneider; Marcelo Heitor Vieira Assad; Sergio Emanuel Kaiser; Ana Maria Lottenberg; Carlos Daniel Magnoni; Marcio Hiroshi Miname; Roberta Soares Lara; Artur Haddad Herdy; Cláudio Gil Soares de Araújo; Mauricio Milani; Miguel Morita Fernandes da Silva; Ricardo Stein; Fernando Antonio Lucchese; Fernando Nobre; Hermilo Borba Griz; Lucélia Batista Neves Cunha Magalhães; Mario Henrique Elesbão de Borba; Mauro Ricardo Nunes Pontes; Ricardo Mourilhe-Rocha Journal: Arq Bras Cardiol Date: 2019-11-04 Impact factor: 2.000