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1.
Clin Infect Dis ; 69(6): 970-979, 2019 08 30.
Artigo em Inglês | MEDLINE | ID: mdl-30508064

RESUMO

BACKGROUND: Recent studies have demonstrated the possibility of negative associations between prior influenza vaccines and subsequent influenza vaccine effectiveness (VE), depending on season and strain. We investigated this association over 4 consecutive influenza seasons (2011-2012 through 2014-2015) in Canada. METHODS: Using a matched test-negative design, laboratory-confirmed influenza cases and matched test-negative controls admitted to hospitals were enrolled. Patients were stratified into 4 groups according to influenza vaccine history (not vaccinated current and prior season [referent], vaccinated prior season only, vaccinated current season only, and vaccinated both current and prior season). Conditional logistic regression was used to estimate VE; prior vaccine impact was assessed each season for overall effect and effect stratified by age (<65 years, ≥65 years) and type/subtype (A/H1N1, A/H3N2, influenza B). RESULTS: Overall, mainly nonsignificant associations were observed. Trends of nonsignificant decreased VE among patients repeatedly vaccinated in both prior and current season relative to the current season only were observed in the A/H3N2-dominant seasons of 2012-2013 and 2014-2015. Conversely, in 2011-2012, during which B viruses circulated, and in 2013-2014, when A/H1N1 circulated, being vaccinated in both seasons tended to result in a high VE in the current season against the dominant circulating subtype. CONCLUSIONS: Prior vaccine impact on subsequent VE among Canadian inpatients was mainly nonsignificant. Even in circumstances where we observed a trend of negative impact, being repeatedly vaccinated was still more effective than not receiving the current season's vaccine. These findings favor continuation of annual influenza vaccination recommendations, particularly in older adults. CLINICAL TRIALS REGISTRATION: NCT01517191.


Assuntos
Hospitalização , Vacinas contra Influenza/imunologia , Influenza Humana/epidemiologia , Influenza Humana/prevenção & controle , Estações do Ano , Vacinação , Idoso , Idoso de 80 Anos ou mais , Canadá/epidemiologia , Estudos de Casos e Controles , Feminino , Humanos , Vírus da Influenza A Subtipo H1N1/imunologia , Vírus da Influenza A Subtipo H3N2/imunologia , Vírus da Influenza B/imunologia , Vacinas contra Influenza/administração & dosagem , Influenza Humana/virologia , Masculino , Pessoa de Meia-Idade , Avaliação de Resultados em Cuidados de Saúde , Vigilância em Saúde Pública , Fatores de Risco
2.
Epidemiol Infect ; 144(3): 537-47, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26168005

RESUMO

Influenza is rarely laboratory-confirmed and the outpatient influenza burden is rarely studied due to a lack of suitable data. We used the Clinical Practice Research Datalink (CPRD) and surveillance data from Public Health England in a linear regression model to assess the number of persons consulting UK general practitioners (GP episodes) for respiratory illness, otitis media and antibiotic prescriptions attributable to influenza during 14 seasons, 1995-2009. In CPRD we ascertained influenza vaccination status in each season and risk status (conditions associated with severe influenza outcomes). Seasonal mean estimates of influenza-attributable GP episodes in the UK were 857 996 for respiratory disease including 68 777 for otitis media, with wide inter-seasonal variability. In an average season, 2·4%/0·5% of children aged <5 years and 1·3%/0·1% of seniors aged ⩾75 years had a GP episode for respiratory illness attributed to influenza A/B. Two-thirds of influenza-attributable GP episodes were estimated to result in prescription of antibiotics. These estimates are substantially greater than those derived from clinically reported influenza-like illness in surveillance programmes. Because health service costs of influenza are largely borne in general practice, these are important findings for cost-benefit assessment of influenza vaccination programmes.


Assuntos
Medicina Geral/estatística & dados numéricos , Vírus da Influenza A , Vírus da Influenza B , Influenza Humana/epidemiologia , Otite Média/epidemiologia , Atenção Primária à Saúde/estatística & dados numéricos , Adolescente , Adulto , Fatores Etários , Idoso , Antibacterianos , Criança , Pré-Escolar , Comorbidade , Bases de Dados Factuais , Prescrições de Medicamentos/estatística & dados numéricos , Humanos , Incidência , Lactente , Recém-Nascido , Vacinas contra Influenza , Influenza Humana/prevenção & controle , Influenza Humana/virologia , Pessoa de Meia-Idade , Otite Média/tratamento farmacológico , Otite Média/virologia , Estações do Ano , Reino Unido/epidemiologia , Vacinação/estatística & dados numéricos , Adulto Jovem
4.
Euro Surveill ; 19(9)2014 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-24626207

RESUMO

During the 2013/14 influenza season in Canada, 631 of 654 hospitalisations for laboratory-confirmed influenza enrolled in sentinel hospitals were due to Influenza A. Of the 375 with known subtype, influenza A(H1N1) accounted for 357. Interim unmatched vaccine effectiveness adjusted for age and presence of one or more medical comorbidities was determined by test-negative case-control design to be 58.5% (90% confidence interval (CI): 43.9-69.3%) overall and 57.9% (90% CI: 37.7-71.5) for confirmed influenza A(H1N1).


Assuntos
Vírus da Influenza A Subtipo H1N1/isolamento & purificação , Vacinas contra Influenza/administração & dosagem , Influenza Humana/epidemiologia , Influenza Humana/prevenção & controle , Avaliação de Resultados em Cuidados de Saúde , Vigilância de Evento Sentinela , Adolescente , Adulto , Idoso , Canadá/epidemiologia , Estudos de Casos e Controles , Criança , Pré-Escolar , Feminino , Hospitalização/estatística & dados numéricos , Humanos , Vírus da Influenza A Subtipo H1N1/imunologia , Vacinas contra Influenza/imunologia , Influenza Humana/virologia , Laboratórios , Masculino , Pessoa de Meia-Idade , Estações do Ano , Índice de Gravidade de Doença , Adulto Jovem
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