BACKGROUND: Since 2011, the Global Influenza Hospital Surveillance Network (GIHSN) has used active surveillance to prospectively collect epidemiological and virological data on patients hospitalized with influenza virus infection. Here, we describe influenza virus strain circulation in the GIHSN participant countries during 2017-2018 season and examine factors associated with complicated hospitalization among patients admitted with laboratory-confirmed influenza illness. METHODS: The study enrolled patients who were hospitalized in a GIHSN hospital in the previous 48 h with acute respiratory symptoms and who had symptoms consistent with influenza within the 7 days before admission. Enrolled patients were tested by reverse transcription-polymerase chain reaction to confirm influenza virus infection. "Complicated hospitalization" was defined as a need for mechanical ventilation, admission to an intensive care unit, or in-hospital death. In each of four age strata (< 15, 15-< 50, 50-< 65, and ≥ 65 years), factors associated with complicated hospitalization in influenza-positive patients were identified by mixed effects logistic regression and those associated with length of hospital stay using a linear mixed-effects regression model. RESULTS: The study included 12,803 hospitalized patients at 14 coordinating sites in 13 countries, of which 4306 (34%) tested positive for influenza. Influenza viruses B/Yamagata, A/H3N2, and A/H1N1pdm09 strains dominated and cocirculated, although the dominant strains varied between sites. Complicated hospitalization occurred in 10.6% of influenza-positive patients. Factors associated with complicated hospitalization in influenza-positive patients included chronic obstructive pulmonary disease (15-< 50 years and ≥ 65 years), diabetes (15-< 50 years), male sex (50-< 65 years), hospitalization during the last 12 months (50-< 65 years), and current smoking (≥65 years). Chronic obstructive pulmonary disease (50-< 65 years), other chronic conditions (15-< 50 years), influenza A (50-< 65 years), and hospitalization during the last 12 months (< 15 years) were associated with a longer hospital stay. The proportion of patients with complicated influenza did not differ between influenza A and B. CONCLUSIONS: Complicated hospitalizations occurred in over 10% of patients hospitalized with influenza virus infection. Factors commonly associated with complicated or longer hospitalization differed by age group but commonly included chronic obstructive pulmonary disease, diabetes, and hospitalization during the last 12 months.

Canadian Center for Vaccinology IWK Health Centre and Nova Scotia Health Authority Dalhousie University Halifax Canada

Center for Vaccine Development and Global Health University of Maryland School of Medicine Baltimore MD USA

CIRI Lyon University Inserm U 1111 Lyon France

Claude Bernard University Lyon France

Department of Science and Technology National Research Foundation Vaccine Preventable Diseases Unit University of the Witwatersrand Johannesburg South Africa

Division of Infectious Diseases Chinese Center for Disease Control and Prevention Beijing China

Emerging Pathogens Laboratory Epidemiology and International Health Fondation Mérieux Centre International de Recherche en Infectiologie Lyon France

FSBI N F Gamaleya NRCEM Moscow Russian Federation

Groupement Hospitalier Edouard Herriot Unité d'Hygiène Epidémiologie et Prévention Hospices Civils de Lyon Lyon France

Hospices Civils de Lyon Croix Rousse University Hospital Infectious Agents Institute Lyon France

Inserm F CRIN Innovative Clinical Research Network in Vaccinology CIC 1417 Paris France

Institute of Health Metrics and Evaluation Department of Health Metrics Sciences University of Washington Seattle WA USA

Medical Research Council Respiratory and Meningeal Pathogens Research Unit School of Pathology Faculty of Health Sciences University of the Witwatersrand Johannesburg South Africa

National Institute of Public Health Prague Czech Republic

National Institutes of Health Mexico City Mexico

Netherlands Institute for Health Services Research Utrecht The Netherlands

OpenHealth Paris France

See more in PubMed

World Health Organization: Influenza (Seasonal). https://www.who.int/en/news-room/fact-sheets/detail/influenza-(seasonal) . Accessed 02 Jul 2019. (2012).

Iuliano AD, Roguski KM, Chang HH, Muscatello DJ, Palekar R, Tempia S, et al. Estimates of global seasonal influenza-associated respiratory mortality: a modelling study. Lancet. 2018;391:1285–1300. doi: 10.1016/S0140-6736(17)33293-2. PubMed DOI PMC

World Health Organization Vaccines against influenza WHO position paper - November 2012. Wkly Epidemiol Rec. 2012;87:461–476. PubMed

Coleman BL, Fadel SA, Fitzpatrick T, Thomas SM. Risk factors for serious outcomes associated with influenza illness in high- versus low- and middle-income countries: systematic literature review and meta-analysis. Influenza Other Respir Viruses. 2018;12:22–29. doi: 10.1111/irv.12504. PubMed DOI PMC

Puig-Barbera J, Tormos A, Sominina A, Burtseva E, Launay O, Ciblak MA, et al. First-year results of the global influenza hospital surveillance network: 2012-2013 northern hemisphere influenza season. BMC Public Health. 2014;14:564. doi: 10.1186/1471-2458-14-564. PubMed DOI PMC

Blanton L, Dugan VG, Abd Elal AI, Alabi N, Barnes J, Brammer L, et al. Update: influenza activity - United States, September 30, 2018-February 2, 2019. MMWR Morb Mortal Wkly Rep. 2019;68:125–134. doi: 10.15585/mmwr.mm6806a1. PubMed DOI PMC

GIHSN: Global Influenza Hospital Surveillance Network. https://www.gihsn.org/ . Accessed 10 Apr 2019. (2019).

Puig-Barbera J, Natividad-Sancho A, Trushakova S, Sominina A, Pisareva M, Ciblak MA, et al. Epidemiology of hospital admissions with influenza during the 2013/2014 northern hemisphere influenza season: results from the global influenza hospital surveillance network. PLoS One. 2016;11:e0154970. doi: 10.1371/journal.pone.0154970. PubMed DOI PMC

Puig-Barbera J, Burtseva E, Yu H, Cowling BJ, Badur S, Kyncl J, et al. Influenza epidemiology and influenza vaccine effectiveness during the 2014–2015 season: annual report from the global influenza hospital surveillance network. BMC Public Health. 2016;16(Suppl 1):757. doi: 10.1186/s12889-016-3378-1. PubMed DOI PMC

Baselga-Moreno V, Trushakova S, McNeil S, Sominina A, Nunes MC, Draganescu A, et al. Influenza epidemiology and influenza vaccine effectiveness during the 2016-2017 season in the global influenza hospital surveillance network (GIHSN) BMC Public Health. 2019;19:487. doi: 10.1186/s12889-019-6713-5. PubMed DOI PMC

GIHSN: Global Influenza Hospital-based Surveillance Network (GIHSN) Core Protocol. https://www.gihsn.org/images/gihsn/GIHSN-Core-Protocol-June-2014.pdf . Accessed 10 Apr 2019 (2013).

Mahoney FI, Barthel DW. Functional evaluation: the Barthel index. Md State Med J. 1965;14:61–65. PubMed

World Health Organization: Influenza. https://www.who.int/immunization/monitoring_surveillance/burden/vpd/WHO_SurveillanceVaccinePreventable_09_Influenza_R2.pdf?ua=1 . Accessed 10 Dec 2019. (2018).

World Health Organization: Influenza transmission zones. https://www.who.int/csr/disease/swineflu/Influenza_transmission_zones.pdf?ua=1 . Accessed 02 Sep 2019 (2011).

Su S, Chaves SS, Perez A, D'Mello T, Kirley PD, Yousey-Hindes K, et al. Comparing clinical characteristics between hospitalized adults with laboratory-confirmed influenza a and B virus infection. Clin Infect Dis. 2014;59:252–255. doi: 10.1093/cid/ciu269. PubMed DOI

Caini S, Kroneman M, Wiegers T, El Guerche-Seblain C, Paget J. Clinical characteristics and severity of influenza infections by virus type, subtype, and lineage: a systematic literature review. Influenza Other Respir Viruses. 2018;12:780–792. doi: 10.1111/irv.12575. PubMed DOI PMC

Puig-Barbera J, Natividad-Sancho A, Launay O, Burtseva E, Ciblak MA, Tormos A, et al. 2012-2013 seasonal influenza vaccine effectiveness against influenza hospitalizations: results from the global influenza hospital surveillance network. PLoS One. 2014;9:e100497. doi: 10.1371/journal.pone.0100497. PubMed DOI PMC

World Health Organization: Recommended composition of influenza virus vaccines for use in the 2017–2018 northern hemisphere influenza season. https://www.who.int/influenza/vaccines/virus/recommendations/2017_18_north/en/ . Accessed 03 Sep 2019 (2017).

World Health Organization: Recommended composition of influenza virus vaccines for use in the 2018 southern hemisphere influenza season. https://www.who.int/influenza/vaccines/virus/recommendations/2018_south/en/. Accessed 03 Sep 2019 (2017).

Jaeger TF. Categorical data analysis: away from ANOVAs (transformation or not) and towards Logit mixed models. J Mem Lang. 2008;59:434–446. doi: 10.1016/j.jml.2007.11.007. PubMed DOI PMC

Beitler PJ, Landis JR. A mixed-effects model for categorical data. Biometrics. 1985;41:991–1000. doi: 10.2307/2530970. PubMed DOI

Martinez A, Soldevila N, Romero-Tamarit A, Torner N, Godoy P, Rius C, et al. Risk factors associated with severe outcomes in adult hospitalized patients according to influenza type and subtype. PLoS One. 2019;14:e0210353. doi: 10.1371/journal.pone.0210353. PubMed DOI PMC

Nichols MK, Andrew MK, Hatchette TF, Ambrose A, Boivin G, Bowie W, et al. Influenza vaccine effectiveness to prevent influenza-related hospitalizations and serious outcomes in Canadian adults over the 2011/12 through 2013/14 influenza seasons: a pooled analysis from the Canadian immunization research network (CIRN) serious outcomes surveillance (SOS network) Vaccine. 2018;36:2166–2175. doi: 10.1016/j.vaccine.2018.02.093. PubMed DOI

The Global Influenza Hospital Surveillance Network: A Multicountry Public Health Collaboration

Predictors of Severity of Influenza-Related Hospitalizations: Results From the Global Influenza Hospital Surveillance Network (GIHSN)