Risk Factors for Severe Outcomes following 2009 Influenza A (H1N1) Infection: A Global Pooled Analysis

Kerkhove, Maria D. Van; Vandemaele, Katelijn; Shinde, Vivek; Jaramillo-Gutierrez, Giovanna; Koukounari, Artemis; Donnelly, Christl A.; Carlino, Luis O.; Owen, Rhonda; Paterson, Beverley J.; Pelletier, Louise; Vachon, Julie; González, Claudia; Yu, Hongjie; Feng, Zijian; Chuang, Shuk-Kwan; Au, Albert Ka-Wing; Buda, Silke; Krause, Gérard; Haas, Walter; Bonmarin, Isabelle; Taniguichi, Kiyosu; Nakajima, Kensuke; Shobayashi, Tokuaki; Takayama, Yoshihiro; Sunagawa, Tomi; Heraud, Jean‐Michel; Orelle, Arnaud; Palacios, E. V.; Sande, Marianne A. B. van der; Wielders, Cornelia C H; Hunt, Darren; Cutter, Jeffrey; Lee, Vernon J.; Thomas, Juno; Santa-Olalla, Patricia; Sierra-Moros, María José; Hanshaoworakul, Wanna; Ungchusak, Kumnuan; Pebody, Richard; Jain, Seema; Mounts, Anthony W.

doi:10.1371/journal.pmed.1001053

Cited by 620 publications

(636 citation statements)

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“…In Ukraine, there was no change in the proportion of severe cases with underlying medical conditions compared to previous seasons. However at 18%, this was much lower than findings of the US Influenza Hospitalization Surveillance Network for this season, where the majority of adult hospitalised cases had at least one reported underlying medical condition,15 and lower than findings from pooled analysis of hospitalised cases from different countries during the 2009 influenza (H1N1) pandemic (31.1%) 16. Obesity was the most commonly reported underlying medical condition in Ukraine for laboratory‐confirmed SARI cases, which was a risk factor identified for severe outcome during the 2009 pandemic16 and has been documented further to be associated with higher risks of intensive care unit admission 17…”

Section: Discussionmentioning

confidence: 56%

Rapid risk assessment during the early weeks of the 2015‐2016 influenza season in Ukraine

Newitt

Mironenko

Holubka

et al. 2018

Influenza Resp Viruses

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BackgroundSeveral eastern European countries reported a severe influenza season to the World Health Organization (WHO) during late 2015. A country‐specific rapid risk assessment for Ukraine was conducted to assess the season's severity and inform public health action.MethodsThe exposure and hazard were assessed using acute respiratory infection (ARI), severe acute respiratory infection (SARI), laboratory surveillance, virological and vaccine data from weeks 40/2015 to 7/2016 with comparison to 4 previous seasons to describe the influenza season start (5‐week consecutive increase in ARI or SARI), predominant virus types, geographical spread and affected age groups.ResultsThe exposure was characterised by an earlier and steeper increase in SARI (week 1/2016) and ARI (week 2/2016) compared to the previous 4 seasons. Transmission was across Ukraine with an increase in ARI and SARI cases aged 30‐64 years compared to 2014/15. Laboratory‐confirmed deaths increased from 11 in 2014/2015 to 342 in 2015/2016; the majority were 30‐64 years old and unvaccinated; and 63.5% had underlying conditions. Total population vaccination coverage was 0.3%. The hazard assessment found influenza virus A(H1N1)pdm09 accounted for >95% of viruses detected. Ukrainian virus strains (n = 62) were antigenically similar to vaccine strains and susceptible to neuraminidase inhibitors.ConclusionsThe first weeks of the 2015/16 influenza season were more severe than previous seasons, with an earlier and steeper increase in severe cases and deaths, particularly in younger adults. Influenza A(H1N1)pdm09 was the predominant strain and was closely related to the seasonal vaccine strain with no evidence of resistance to antiviral drugs.

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Section: Discussionmentioning

confidence: 56%

Rapid risk assessment during the early weeks of the 2015‐2016 influenza season in Ukraine

Newitt

Mironenko

Holubka

et al. 2018

Influenza Resp Viruses

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“…Second, as the present study was observational, other unrecognised confounders may affect our findings. For example, obesity has emerged as a risk factor for hospitalisation and severe outcomes in pH1N1 cases [34][35][36]. It remains unclear from the pH1N1 literature whether obesity is an independent risk factor for influenza or whether the association between obesity and severe outcomes of influenza is itself confounded by diabetes, cardiovascular disease and other obesity-related comorbidities [36].…”

Section: Discussionmentioning

confidence: 99%

“…For example, obesity has emerged as a risk factor for hospitalisation and severe outcomes in pH1N1 cases [34][35][36]. It remains unclear from the pH1N1 literature whether obesity is an independent risk factor for influenza or whether the association between obesity and severe outcomes of influenza is itself confounded by diabetes, cardiovascular disease and other obesity-related comorbidities [36]. One recent study of the NHANES cohort found a consistent association between obesity and pH1N1 hospitalisations/death, after stratifying by comorbidity, suggesting a true diathesis [34].…”

Section: Discussionmentioning

confidence: 99%

Working-age adults with diabetes experience greater susceptibility to seasonal influenza: a population-based cohort study

et al. 2014

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Aims/hypothesis The aim of this work was to compare the incidence of illness attributable to influenza in working-age adults (age <65 years) with and without diabetes. Methods We performed a cohort study using administrative data from Manitoba, Canada, between 2000 and 2008. All working-age adults with diabetes were identified and matched with up to two non-diabetic controls. We analysed the rates of influenza-like illness physician visits and hospitalisations, pneumonia and influenza hospitalisations, and all-cause hospitalisations. Multivariable regressions were used to estimate the influenza-attributable rate of each outcome. Results We included 745,777 person-years of follow-up among 166,715 subjects. The median age was 50-51 years and 48-49% were women; adults with diabetes had more comorbidities and were more likely to be vaccinated for influenza than those without diabetes. Compared with similar adults without diabetes, those with diabetes had a 6% greater (RR 1.06, 95% CI 1.02, 1.10; absolute risk difference 6 per 1,000 adults per year) increase in all-cause hospitalisations associated with influenza, representing a total of 54 additional hospitalisations. There were no differences in the influenzaattributable rates of influenza-like illness (p = 0.06) or pneumonia and influenza (p = 0.11). Conclusions/interpretation Guidelines calling for influenza vaccinations in diabetic, in addition to elderly, adults implicitly single out working-age adults with diabetes. The evidence supporting such guidelines has hitherto been scant. We found that working-age adults with diabetes appear more susceptible to serious influenza-attributable illness. These findings represent the strongest available evidence for targeting diabetes as an indication for influenza vaccination, irrespective of age.

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“…Because different studies used different age categories for reporting seropositivity results in their individual publications, we requested all researchers to share their seropositivity results for five age categories (0–4; 5–19; 20–44; 45–64, and ≥65 years old) to ensure comparability. These age categories were chosen based on differences in the epidemiology and reported clinical severity of the disease in these age groups 19. Overall pooled estimates were age‐adjusted using age‐specific population estimates from the UN 20.…”

Section: Methodsmentioning

confidence: 99%

Estimating age‐specific cumulative incidence for the 2009 influenza pandemic: a meta‐analysis of A(H1N1)pdm09 serological studies from 19 countries

Kerkhove¹,

Hirve

Koukounari

et al. 2013

Influenza Resp Viruses

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162

136

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BackgroundThe global impact of the 2009 influenza A(H1N1) pandemic (H1N1pdm) is not well understood.ObjectivesWe estimate overall and age‐specific prevalence of cross‐reactive antibodies to H1N1pdm virus and rates of H1N1pdm infection during the first year of the pandemic using data from published and unpublished H1N1pdm seroepidemiological studies.MethodsPrimary aggregate H1N1pdm serologic data from each study were stratified in standardized age groups and evaluated based on when sera were collected in relation to national or subnational peak H1N1pdm activity. Seropositivity was assessed using well‐described and standardized hemagglutination inhibition (HI titers ≥32 or ≥40) and microneutralization (MN ≥ 40) laboratory assays. The prevalence of cross‐reactive antibodies to the H1N1pdm virus was estimated for studies using sera collected prior to the start of the pandemic (between 2004 and April 2009); H1N1pdm cumulative incidence was estimated for studies in which collected both pre‐ and post‐pandemic sera; and H1N1pdm seropositivity was calculated from studies with post‐pandemic sera only (collected between December 2009–June 2010).ResultsData from 27 published/unpublished studies from 19 countries/administrative regions – Australia, Canada, China, Finland, France, Germany, Hong Kong SAR, India, Iran, Italy, Japan, Netherlands, New Zealand, Norway, Reunion Island, Singapore, United Kingdom, United States, and Vietnam – were eligible for inclusion. The overall age‐standardized pre‐pandemic prevalence of cross‐reactive antibodies was 5% (95%CI 3–7%) and varied significantly by age with the highest rates among persons ≥65 years old (14% 95%CI 8–24%). Overall age‐standardized H1N1pdm cumulative incidence was 24% (95%CI 20–27%) and varied significantly by age with the highest in children 5–19 (47% 95%CI 39–55%) and 0–4 years old (36% 95%CI 30–43%).ConclusionsOur results offer unique insight into the global impact of the H1N1 pandemic and highlight the need for standardization of seroepidemiological studies and for their inclusion in pre‐pandemic preparedness plans. Our results taken together with recent global pandemic respiratory‐associated mortality estimates suggest that the case fatality ratio of the pandemic virus was approximately 0·02%.

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Risk Factors for Severe Outcomes following 2009 Influenza A (H1N1) Infection: A Global Pooled Analysis

Cited by 620 publications

References 56 publications

Rapid risk assessment during the early weeks of the 2015‐2016 influenza season in Ukraine

Rapid risk assessment during the early weeks of the 2015‐2016 influenza season in Ukraine

Working-age adults with diabetes experience greater susceptibility to seasonal influenza: a population-based cohort study

Estimating age‐specific cumulative incidence for the 2009 influenza pandemic: a meta‐analysis of A(H1N1)pdm09 serological studies from 19 countries

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