Assessing the severity of the novel influenza A/H1N1 pandemic

Garske, Tini; Legrand, Judith; Donnelly, Christl A.; Ward, Helen; Cauchemez, Simon; Fraser, Christophe; Ferguson, Neil M.; Ghani, Azra C.

doi:10.1136/bmj.b2840

Cited by 226 publications

(251 citation statements)

References 14 publications

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“…El amplio periodo de tiempo transcurrido entre el primer caso confirmado y la primera defunción confirmada se debe a la demora en el reporte de las defunciones por influenza, situación que también se ha observado en otros países, como Estados Unidos, Canadá y Reino Unido. 22 La mortalidad, al igual que la morbilidad, afectó en particular a los menores de 40 años, ya que 65% de los fallecimientos correspondió a personas hasta los 39 años y 45.1% se presentó en adultos jóvenes, entre los 20 y 39 años. La media de la tasa de mortalidad en el periodo del 10 de abril al 31 de mayo fue de 1.1 casos por millón de habitantes; no obstante, dicha tasa fue superior a la media en los grupos de edad entre los 20 y los 59 años, en los que fluctuó entre 1.5 y 1.9 por millón.…”

Section: Discussionunclassified

Perfil epidemiológico de la mortalidad por influenza humana A (H1N1) en México

Fajardo-Dolci¹,

Hernández-Torres²,

Santacruz-Varela³

et al. 2009

Salud pública Méx

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Section: Discussionunclassified

Perfil epidemiológico de la mortalidad por influenza humana A (H1N1) en México

Fajardo-Dolci¹,

Hernández-Torres²,

Santacruz-Varela³

et al. 2009

Salud pública Méx

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“…Additionally, these estimates can be used as denominators in METHODS NIHR Journals Library www.journalslibrary.nihr.ac.uk measurements of pandemic severity including age-specific rates of influenza hospitalisations and the case fatality proportion. 16 Our findings will additionally be presented to key decision-makers through the researchers' positions on government advisory committees and links with key policy-makers.…”

Section: Phase 4 (Ongoing)mentioning

confidence: 99%

Population-level susceptibility, severity and spread of pandemic influenza: design of, and initial results from, a pre-pandemic and hibernating pandemic phase study using cross-sectional data from the Health Survey for England (HSE)

Fragaszy

Quinlivan

Breuer³

et al. 2015

Public Health Res

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BackgroundAssessing severity and spread of a novel influenza strain at the start of a pandemic is critical for informing a targeted and proportional response. It requires community-level studies to estimate the burden of infection and disease. Rapidly initiating such studies in a pandemic is difficult. The study aims to establish an efficient system allowing real-time assessment of population susceptibility, spread of infection and clinical attack rates in the event of a pandemic.MethodsWe developed and appended additional survey questions and specimen collection to the Health Survey for England (HSE) – a large, annual, rolling nationally representative general population survey recruiting throughout the year – to enable rapid population-based surveys of influenza infection and disease during a pandemic. Using these surveys we can assess the spread of the virus geographically, by age and through time. The data generated can also provide denominators for national estimates of case fatality and hospitalisation rates.Phase 1: we compared retrospectively collected HSE illness rates during the first two infection waves of the 2009 pandemic with the Flu Watch study (a prospective community cohort). Monthly and seasonal age-specific rates of illness and proportion vaccinated were compared.Phase 2: we piloted blood specimen and data collection alongside the 2012–13 HSE. We are developing laboratory methods and protocols for real-time serological assays of a novel pandemic influenza virus using these specimens, and automated programmes for analysing and reporting illness and infection rates.Phase 3: during inter-pandemic years, the study enters a holding phase, where it is included in the yearly HSE ethics application and planning procedures, allowing rapid triggering in a pandemic.Phase 4: once retriggered, the study will utilise the methods developed in phase 2 to monitor the severity and spread of the pandemic in real time.ResultsPhase 1: the rates of reported illness during the first two waves in the HSE underestimated the community burden as measured by Flu Watch, but the patterns of illness by age and time were broadly comparable. The extent of underestimation was greatest for HSE participants interviewed later in the year compared with those interviewed closer to the pandemic. Vaccine uptake in the HSE study was comparable to independent national estimates and the Flu Watch study.Phases 2 and 3: illness data and serological samples from 2018 participants were collected in the 2012–13 HSE and transferred to the University College London Hospital. In the 2013 HSE and onwards, this project was included in the annual HSE ethics and planning rounds.ConclusionsThe HSE’s underestimation of illness rates during the first two waves of the pandemic is probably due to recall bias and the limitation of being able to report only one illness when multiple illnesses per season can occur. Changes to the illness questions (reporting only recent illnesses) should help minimise these issues. Additional prospective follow-up could improve measurement of disease incidence. The representative nature of the HSE allows accurate measurements of vaccine uptake.Study registrationThis study is registered as ISRCTN80214280.FundingThis project was funded by the NIHR Public Health Research programme and will be published in full inPublic Health Research; Vol. 3, No. 6. See the NIHR Journals Library website for further project information.

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“…The global spread of the 2009 novel pandemic influenza A (H1N1) virus [8] led to the accelerated production of monovalent 2009 Influenza A (H1N1) vaccines (pH1N1) by manufacturers in the Americas, Europe, and Asia [9]. Rapid and extensive vaccine administration was implemented worldwide.…”

Section: Introductionmentioning

confidence: 99%