Patients Hospitalized With Laboratory-Confirmed Influenza During the 2010-2011 Influenza Season: Exploring Disease Severity by Virus Type and Subtype

Chaves, Sandra S.; Aragon, Deborah; Bennett, Nancy M.; Cooper, Tara; D’Mello, Tiffany; Farley, Monica M.; Fowler, Brian; Hancock, Emily B.; Kirley, Pam Daily; Lynfield, Ruth; Ryan, Patricia; Schaffner, William; Sharangpani, Ruta; Tengelsen, Leslie; Thomas, Ann; Thurston, Diana; Williams, Jean; Yousey-Hindes, Kimberly; Zansky, Shelley; Finelli, Lyn

doi:10.1093/infdis/jit316

Cited by 107 publications

(130 citation statements)

References 27 publications

Supporting

Mentioning

108

Contrasting

Unclassified

Order By: Relevance

“…Influenza disease severity in our study was associated with A/H1N1pdm09 infection, and this association persisted beyond the immediate postpandemic period. Our findings are consistent with the results of a large, population-based cohort study of influenza surveillance in the United States (30).…”

Section: Original Researchsupporting

confidence: 91%

“…In this study, initiated during the first season after the 2009 pandemic, patients infected with A/H1N1pdm09 were more likely to have severe disease, compared with those infected with other influenza A subtypes and influenza B (30). In subSaharan Africa, limited data exist on the severity of infection caused by different influenza virus subtypes (31).…”

Section: Original Researchmentioning

confidence: 91%

See 1 more Smart Citation

Epidemiologic and Spatiotemporal Characterization of Influenza and Severe Acute Respiratory Infection in Uganda, 2010-2015

Cummings¹,

Bakamutumaho

Kayiwa

et al. 2016

Annals ATS

View full text Add to dashboard Cite

Rationale: Little is known about the epidemiology of severe acute respiratory infection (SARI) or influenza in sub-Saharan Africa. Characterization of influenza transmission dynamics and risk factors for severe disease and mortality is critical to inform prevention and mitigation strategies.Objectives: To characterize the epidemiology and transmission dynamics of influenza and risk factors for influenza-associated severe respiratory infection in Uganda.Methods: Clinicians at 12 sentinel surveillance sites prospectively collected clinical data and upper respiratory tract samples from consecutive patients who met criteria for SARI and influenza-like illness (ILI). Samples were tested for influenza A and B viruses using real-time reverse transcription-polymerase chain reaction. Spatial and spatiotemporal cluster modeling was performed to identify loci of increased influenza transmission. Morbidity and mortality were assessed through chart review in a defined subset of patients. Univariable and multivariable analyses were used to identify risk factors for severe respiratory infection, prolonged hospitalization, and in-hospital mortality. Measurements and Main Results:From October 2010 to June 2015, 9,978 patients met case definitions for SARI and ILI and had samples tested for influenza A and B. Of the 9,978 patient samples tested, 1,113 (11.2%) were positive for influenza. Among 6,057 patients with ILI, 778 samples (12.8%) were positive, and among 3,921 patients with SARI, 335 samples (8.5%) were positive. Significant clustering of influenza cases was observed in urban and periurban areas and during rainy seasons. Among 1,405 cases of SARI with available outcome data, in-hospital mortality was 1.6%. Infection with the 2009 pandemic A/H1N1 subtype and prolonged time to presentation were independently associated with SARI among influenza cases.Conclusions: Influenza is associated with a substantial proportion of acute respiratory infection in Uganda. As influenza vaccination programs are developed in East Africa, timing campaigns to confer protection during rainy seasons should be considered, particularly among high-risk urban populations.

show abstract

Section: Original Researchsupporting

confidence: 91%

Section: Original Researchmentioning

confidence: 91%

Epidemiologic and Spatiotemporal Characterization of Influenza and Severe Acute Respiratory Infection in Uganda, 2010-2015

Cummings¹,

Bakamutumaho

Kayiwa

et al. 2016

Annals ATS

View full text Add to dashboard Cite

show abstract

“…In addition, the number of patients in this age‐group admitted to the ICU was higher in A(H1N1)pdm09 dominant seasons compared with other subtype seasons 26, 27…”

Section: Discussionmentioning

confidence: 88%

Estimating the burden of seasonal influenza in Spain from surveillance of mild and severe influenza disease, 2010‐2016

Oliva

Delgado-Sanz

Larrauri

2017

Influenza Resp Viruses

View full text Add to dashboard Cite

BackgroundEstimating the national burden of influenza disease is challenging. We aimed to estimate the disease burden of seasonal influenza in Spain, at the primary care and hospital level, over the 6 influenza seasons after 2009 pandemic.MethodsWe used data from the Spanish Influenza Sentinel Surveillance System to estimate weekly influenza rates and the number of influenza‐like illness (ILI) and mild confirmed influenza cases (MCIC). From the surveillance of severe hospitalized confirmed influenza cases (SHCIC), we obtained hospitalization rates and total number of SHCIC, intensive care unit (ICU) admissions and deaths in influenza hospitalized patients. We estimated both mild and severe influenza cases, overall, and by age‐group (<5, 5‐14, 15‐64, and ≥65 years).ResultsThe highest cumulative rates of MCIC were observed in <15 years (1395‐3155 cases/100 000 population in 5‐14 years) and the lowest in ≥65 years (141‐608 cases/100 000 population). SHCIC rates revealed a characteristic U‐shaped distribution, with annual average hospitalization rates of 16.5 and 18.9 SHCIC/100, 000 p in 0‐4 years, and ≥65 years, respectively. We estimated an annual average of 866 868 cases of ILI attended in primary care (55% were MCIC), 3616 SHCIC, 1232 ICU admissions, and 437 deaths in SHCIC. The percentage of ICU admission among SHCIC was highest at 15‐64 years (42%), while the hospitalization fatality rate ranged from 1% in 0‐4 years to 18% in ≥65 years.ConclusionsThe ongoing Spanish Influenza Surveillance System allowed obtaining crucial information regarding the impact of mild and severe influenza in Spain.

show abstract

“…Clinical and epidemiological reports provide a complex picture of the impacts of different seasonal influenza virus (sub)types on infection risk and disease severity, with both influenza A and B viruses contributing to morbidity and mortality (21,(29)(30)(31)(32)(33)(34). However, the understanding of disease due to seasonal influenza viruses in "normal" cases (nonhospitalized patients with nonfatal cases) is limited.…”

Section: Discussionmentioning

confidence: 99%

Characterization of the Localized Immune Response in the Respiratory Tract of Ferrets following Infection with Influenza A and B Viruses

Carolan

Rockman

Borg

et al. 2016

J Virol

View full text Add to dashboard Cite

The burden of infection with seasonal influenza viruses is significant. Each year is typically characterized by the dominance of one (sub)type or lineage of influenza A or B virus, respectively. The incidence of disease varies annually, and while this may be attributed to a particular virus strain or subtype, the impacts of prior immunity, population differences, and variations in clinical assessment are also important. To improve our understanding of the impacts of seasonal influenza viruses, we directly compared clinical symptoms, virus shedding, and expression of cytokines, chemokines, and immune mediators in the upper respiratory tract (URT) of ferrets infected with contemporary A(H1N1)pdm09, A(H3N2), or influenza B virus. Gene expression in the lower respiratory tract (LRT) was also assessed. Clinical symptoms were minimal. Overall cytokine/chemokine profiles in the URT were consistent in pattern and magnitude between animals infected with influenza A and B viruses, and peak expression levels of interleukin-1␣ (IL-1␣), IL-1␤, IL-6, IL-12p40, alpha interferon (IFN-␣), IFN-␤, and tumor necrosis factor alpha (TNF-␣) mRNAs correlated with peak levels of viral shedding. MCP1 and IFN-␥ were expressed after the virus peak. Granzymes A and B and IL-10 reached peak expression as the virus was cleared and seroconversion was detected. Cytokine/chemokine gene expression in the LRT following A(H1N1)pdm09 virus infection reflected the observations seen for the URT but was delayed 2 or 3 days, as was virus replication. These data indicate that disease severities and localized immune responses following infection with seasonal influenza A and B viruses are similar, suggesting that other factors are likely to modulate the incidence and impact of seasonal influenza. IMPORTANCEBoth influenza A and B viruses cocirculate in the human population, and annual influenza seasons are typically dominated by an influenza A virus subtype or an influenza B virus lineage. Surveillance data indicate that the burden of disease is higher in some seasons, yet it is unclear whether this is due to specific virus strains or to other factors, such as cross-reactive immunity or clinical definitions of influenza. We directly compared disease severities and localized inflammatory responses to different seasonal influenza virus strains, including the 2009 pandemic strain, in healthy naive ferrets. We found that the disease severities and the cytokine and chemokine responses were similar irrespective of the seasonal strain or the location of the infection in the respiratory tract. This suggests that factors other than the immune response to a particular virus (sub)type contribute to the variable impact of influenza virus infection in a population. Morbidity and mortality associated with human influenza virus infection are significant worldwide. Influenza is caused by three virus types (A, B, and C), among which types A and B are responsible for most of the diagnosed cases of seasonal influenza. Influenza A viruses attract the greatest attentio...

show abstract

Patients Hospitalized With Laboratory-Confirmed Influenza During the 2010-2011 Influenza Season: Exploring Disease Severity by Virus Type and Subtype

Abstract: During the 2010-2011 season, pH1N1 caused more severe disease than H3N2 or B in hospitalized patients. Underlying medical conditions increased severity despite virus strain. Antiviral treatment reduced severity among adults. Our findings underscore the importance of influenza prevention.

Cited by 107 publications

References 27 publications

Epidemiologic and Spatiotemporal Characterization of Influenza and Severe Acute Respiratory Infection in Uganda, 2010-2015

Epidemiologic and Spatiotemporal Characterization of Influenza and Severe Acute Respiratory Infection in Uganda, 2010-2015

Estimating the burden of seasonal influenza in Spain from surveillance of mild and severe influenza disease, 2010‐2016

Characterization of the Localized Immune Response in the Respiratory Tract of Ferrets following Infection with Influenza A and B Viruses

Contact Info

Product

Resources

About