Early estimates of the excess mortality associated with the 2008-9 influenza season in Portugal

Nogueira, Paulo; Nunes, Baltazar; Machado, Ausenda; Rodrigues, Emanuel; Gómez, Verónica; Sousa, Leandro; Falcão, José Marinho

doi:10.2807/ese.14.18.19194-en

Cited by 22 publications

(15 citation statements)

References 1 publication

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“…Another important point to note is the fact that the impact of influenza epidemics in Portugal was relatively well captured in the all-cause mortality time series. This result supports the use of this indicator for influenza surveillance purposes in Portugal, in particular to give near real-time estimates of inter-pandemic and pandemic influenza mortality impact [42], [43], [44]. We note that all-cause mortality is less dependent on diagnostic and coding differences between countries, time periods, or during unusual events like pandemics, as compared with cause-specific indicators.…”

Section: Discussionsupporting

confidence: 79%

Excess Mortality Associated with Influenza Epidemics in Portugal, 1980 to 2004

et al. 2011

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BackgroundInfluenza epidemics have a substantial impact on human health, by increasing the mortality from pneumonia and influenza, respiratory and circulatory diseases, and all causes. This paper provides estimates of excess mortality rates associated with influenza virus circulation for 7 causes of death and 8 age groups in Portugal during the period of 1980–2004.Methodology/Principal FindingsWe compiled monthly mortality time series data by age for all-cause mortality, cerebrovascular diseases, ischemic heart diseases, diseases of the respiratory system, chronic respiratory diseases, pneumonia and influenza. We also used a control outcome, deaths from injuries. Age- and cause-specific baseline mortality was modelled by the ARIMA approach; excess deaths attributable to influenza were calculated by subtracting expected deaths from observed deaths during influenza epidemic periods. Influenza was associated with a seasonal average of 24.7 all-cause excess deaths per 100,000 inhabitants, approximately 90% of which were among seniors over 65 yrs. Excess mortality was 3–6 fold higher during seasons dominated by the A(H3N2) subtype than seasons dominated by A(H1N1)/B. High excess mortality impact was also seen in children under the age of four years. Seasonal excess mortality rates from all the studied causes of death were highly correlated with each other (Pearson correlation range, 0.65 to 0.95, P<0.001) and with seasonal rates of influenza-like-illness (ILI) among seniors over 65 years (Pearson correlation rho>0.64, P<0.05). By contrast, there was no correlation with excess mortality from injuries.Conclusions/SignificanceOur excess mortality approach is specific to influenza virus activity and produces influenza-related mortality rates for Portugal that are similar to those published for other countries. Our results indicate that all-cause excess mortality is a robust indicator of influenza burden in Portugal, and could be used to monitor the impact of influenza epidemics in this country. Additional studies are warranted to confirm these findings in other settings.

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Section: Discussionsupporting

confidence: 79%

Excess Mortality Associated with Influenza Epidemics in Portugal, 1980 to 2004

et al. 2011

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“…In two or three other countries an excess of mortality was also observed, especially among those older than 75 years of age. It should be emphasised that this pattern has previously been observed with A(H3N2) viruses, for example in Portugal in 2008−2009 [16].…”

Section: Mortality From All Causessupporting

confidence: 75%

Clinical Presentation of Influenza in Children 6 to 35 Months of Age

Danier

Rivera

Claeys

et al. 2019

Pediatric Infectious Disease Journal

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Background: In an exploratory analysis of an inactivated quadrivalent influenza vaccine (IIV4) trial in children 6–35 months without risk factors for influenza, we evaluated clinical presentation of influenza illness and vaccine impact on health outcomes. Methods: This phase III trial was conducted in 13 geographically diverse countries across 5 influenza seasons (2011–2014). Children were randomized 1:1 to IIV4 or control. Active surveillance was performed for influenza-like episodes (ILE); influenza was confirmed by reverse transcription polymerase chain reaction (RT-PCR). The total vaccinated cohort was evaluated (N = 12,018). Results: 5702 children experienced ≥1 ILE; 356 (IIV4 group) and 693 (control group) children had RT-PCR-confirmed influenza. Prevalence of ILE was similar in RT-PCR-positive and RT-PCR-negative cases regardless of vaccination. Breakthrough influenza illness was attenuated in children vaccinated with IIV4; moderate-to-severe illness was 41% less likely to be reported in the IIV4 group than the control group [crude odds ratio: 0.59 (95% confidence intervals: 0.44−0.77)]. Furthermore, fever >39°C was 46% less frequent following vaccination with IIV4 than with control [crude odds ratio: 0.54 (95% confidence intervals: 0.39−0.75)] in children with breakthrough illness. Health outcome analysis showed that, each year, IIV4 would prevent 54 influenza cases per 1000 children and 19 children would need to be vaccinated to prevent 1 new influenza case. Conclusions: In addition to preventing influenza in 50% of participants, IIV4 attenuated illness severity and disease burden in children who had a breakthrough influenza episode despite vaccination.

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“…The identification of influenza epidemics requires influenza surveillance data, with information on influenza virus type, and influenza epidemic activity period . Also, and when available, the identification of other events that contribute to mortality or hospitalizations distribution, like secular trend or seasonality, is desirable so to get a better fit of the model to the time series and improve the quality and the validity of the influenza attributable excess estimate …”

Section: Introductionmentioning

confidence: 99%

“…In Portugal, there are several studies that associate this respiratory infection with excess pneumonia and influenza (P&I) and all‐causes mortality . However, information on influenza impact on morbidity indicators, such as hospital admissions, is scarce and the knowledge of influenza impact and the role of immunization on hospitalizations is essential for a better resource management and for preparing mitigation measures.…”

Section: Introductionmentioning

confidence: 99%

Excess pneumonia and influenza hospitalizations associated with influenza epidemics in Portugal from season 1998/1999 to 2014/2015

Rodrigues

Machado

Silva

et al. 2018

Influenza Resp Viruses

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BackgroundThe aim of this study was to estimate excess pneumonia and influenza (P&I) hospitalizations during influenza epidemics and measure their correlation with influenza vaccine coverage in the 65 and more years old, according to the type/subtype of influenza virus.MethodsThe study period comprised week 40/1998‐40/2015. Age‐specific weekly P&I hospitalizations (ICD‐9: 480‐487) as main diagnosis were extracted from the National Hospital Discharge database. Age‐specific baseline hospitalization rates were estimated by autoregressive integrated moving average (ARIMA) model without time periods with excess hospitalizations. Excess hospitalizations were calculated by subtracting expected hospitalization rates from the observed during influenza epidemic periods. Correlation between excess P&I hospitalizations and influenza vaccine coverage in the elderly was measured with Pearson correlation coefficient.ResultsThe average excess P&I hospitalizations/season was 19.4/105 (range 0‐46.1/105), and higher excess was observed in young children with <2 years (79.8/105) and ≥65 years (68.3/105). In epidemics with A(H3) dominant, the highest excess hospitalizations were observed among 65 and over. Seasons which influenza B or A(H1)pdm09 dominance the highest excess was observed in children with <2 years. High negative correlation was estimated between excess hospitalizations associated with A(H3) circulation and vaccine coverage in the elderly (r = −.653; 95% CI: −0.950 to −0.137).ConclusionOver 80% of the influenza epidemics were associated with excess hospitalizations. However, excess P&I hospitalizations pattern differed from age group and circulating virus. This ecologic approach also identified a reduction in excess P&I associated with A(H3) circulation with increasing vaccine coverage in the elderly.

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Early estimates of the excess mortality associated with the 2008-9 influenza season in Portugal

Cited by 22 publications

References 1 publication

Excess Mortality Associated with Influenza Epidemics in Portugal, 1980 to 2004

Excess Mortality Associated with Influenza Epidemics in Portugal, 1980 to 2004

Clinical Presentation of Influenza in Children 6 to 35 Months of Age

Excess pneumonia and influenza hospitalizations associated with influenza epidemics in Portugal from season 1998/1999 to 2014/2015

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