Clinical profile and outcome of patients admitted with swine-origin Influenza A H1N1 virus infection at a tertiary care hospital in Western India

Ambika Sharma, R. S. Mathur


Background: Most of the studies on swine flu H1N1 have been done during the pandemic phase. There was a sudden upsurge in virus activity in 2015 at many centers in India. The present study was designed to assess the current status and pattern of H1N1 infection. The primary objective of this study is to study the clinical profile of patients admitted with Swine-origin influenza A (H1N1) virus infection and Secondary objective is to study the clinical outcome in terms of morbidity and mortality.

Methods: This was a retrospective observational study done at a tertiary care centre from March 2015 to April 2016. All admitted and confirmed cases of H1N1 swine flu infection were studied for demographic details, co-existing medical conditions and clinical presentation. Data regarding the course of disease, complications, treatments and outcomes were recorded from the clinical record.

Results: Common presenting symptoms were cough and fever (95%). Common findings were fever (62.5%), tachycardia, tachypnea and crepitation on auscultation (58.5%). Associated comorbidities were Diabetes mellitus (19.5%), Chronic kidney disease (17%), immunosuppression (9.8%). Consolidation was seen in nearly half of the patients on radiological imaging. Complications noted in our patients were pneumonia (45%), respiratory failure (31%) and ARDS (14.6%). Seventeen percent of patients required non-invasive and invasive mechanical ventilation. Around 25 percent of cases, required ICU admission while two patients died during the hospital stay.

Conclusions: The study emphasizes and restates the morbidities caused by H1N1 swine influenza infection as nearly half of the patients in this study experienced severe illness and complications.


Clinical profile, Complications, Influenza H1N1, Swine flu

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Temte JL, Prunuske JP. Seasonal influenza in primary care settings: review for primary care physicians. Wisconsin Med J. 2010;109(4):193-200.

Patient A. Swine influenza A (H1N1) infection in two children-Southern California, March-April 2009. Morbidity Mortality Weekly Report. 2009;58:400-2.

Centers for Disease Control and Prevention (CDC. Outbreak of swine-origin influenza A (H1N1) virus infection-Mexico, March-April 2009. MMWR. Morb Mortal Wkly Rep. 2009;58(17):467-70.

Dawood FS, Jain S, Finelli L, Shaw MW, Lindstrom S, Garten RJ, et al. Novel Swine-Origin Influenza A (H1N1) Virus Investigation Team; Emergence of a novel swine-origin influenza A (H1N1) virus in humans. N Engl J Med. 2009;360:2605-15.

Garten RJ, Davis CT, Russell CA, Shu B, Lindstrom S, Balish A, et al. Antigenic and genetic characteristics of swine-origin 2009 A (H1N1) influenza viruses circulating in humans. Sci. 2009;325(5937):197-201.

ANZIC Influenza Investigators. Webb SA, Aubron C, Bailey M, Bellomo R, Howe B, McArthur C, et al. Critical care services and the H1N1 (2009) influenza epidemic in Australia and New Zealand in 2010: The impact of the second winter epidemic. Crit Care. 2011;15(3):R143.

Kumar A, Zarychanski R, Pinto R, Cook DJ, Marshall J, Lacroix J, et al. Critically ill patients with 2009 influenza A (H1N1) infection in Canada. JAMA. 2009;302(17):1872-9.

Louie JK, Acosta M, Winter K, Jean C, Gavali S, Schechter R, et al. Factors associated with death or hospitalization due to pandemic 2009 influenza A (H1N1) infection in California. JAMA. 2009;302(17):1896-902.

Zarychanski R, Stuart TL, Kumar A, Doucette S, Elliott L, Kettner J, Plummer F. Correlates of severe disease in patients with 2009 pandemic influenza (H1N1) virus infection. CMAJ. 2010;182(3):257-64.

Domínguez-Cherit G, Lapinsky SE, Macias AE, Pinto R, Espinosa-Perez L, de la Torre A, et al. Critically ill patients with 2009 influenza A (H1N1) in Mexico. JAMA. 2009;302(17):1880-7.

Nath A, Hashim Z, Khan A, Mangla L, Azim A, Khare V, et al. Resurgence of Viral Activity of Pandemic Influenza a (H1N1) 2009: a report from a tertiary care institute in North India. Austin J Pulm Respir Med. 2017; 4(1):1050.

Mehta AA, Kumar VA, Nair SG, Joseph FK, Kumar G, Singh SK. Clinical profile of patients admitted with swine-origin influenza A (H1N1) virus infection: an experience from a tertiary care hospital. JCDR. 2013;7(10):2227-30.

Samra T, Pawar M, Yadav A. One year of experience with H1N1 Infection: clinical observations from a tertiary care hospital in Northern India. Ind J Community Med. 2011;36(3):241-3.

Chudasama RK, Patel UV, Verma PB, Amin CD, Savaria D, Ninama R, et al. Clinico-epidemiological features of the hospitalized patients with 2009 pandemic influenza A (H1N1) virus infection in Saurashtra region, India (September 2009 to February 2010). Lung India: Ind Chest Soc. 2011;28(1):11.

Jagannatha SR, Rao MJ, Swamy N, Umapathy BL. Profile of H1N1 infection in a tertiary care center. Ind J Pathol Microbiol. 2011;54(2):323-5.

Puvanalingam A, Rajendiran C, Sivasubramanian K, Ragunanthanan S, Suresh S, Gopalakrishnan S. Case series study of the clinical profile of H1N1 swine flu influenza. J Assoc Physicians India. 2011;59(8):14-6.

Patel KK, Patel AK, Mehta PM, Amin RP, Patel KP, Chuhan PC, et al. Clinical outcome of novel H1N1 (Swine Flu)-infected patients during 2009 pandemic at tertiary referral hospital in western India. J Glob Infect Dis. 2013;5(3):93-7.

Crum-Cianflone NF, Blair PJ, Faix D, Arnold J, Echols S, Sherman SS, et al. Clinical and epidemiologic characteristics of an outbreak of novel H1N1 (swine origin) influenza A virus among United States military beneficiaries. Clin Infect Dis. 2009;49(12):1801-10.

World Health Organization. Human infection with new influenza A (H1N1) virus: clinical observations from a school-associated outbreak in Kobe, Japan, May 2009. Weekly Epidemiol Rec. 2009;84(24):237-48.

World Health Organization. Human infection with new influenza A (H1N1) virus: clinical observations from Mexico and other affected countries, May 2009. Weekly Epidemiol Rec. 2009;84(21):185-9.

Siddharth V, Goyal V, Koushal VK. Clinical-epidemiological profile of influenza A H1N1 cases at a tertiary care institute of India. Indian J Community Med. 2012;37(4):232-5.

Mathur S, Dubey T, Kulshrestha M, Agarwal H, Mathur G, Mathur A, et al. Clinical profile and mortality among novel influenza A (H1N1) infected patients: 2009-2010 Jodhpur, Rajasthan pandemic. J Assoc Physicians India. 2013;61(9):627-32.

Centers for Disease Control and Prevention (CDC). Hospitalized patients with novel influenza A (H1N1) virus infection - California, April-May 2009. MMWR Morb Mortal Wkly Rep. 2009;58(19):536-41.

Indavarapu A, Akinapelli A. Neutrophils to lymphocyte ratio as a screening tool for swine influenza. Indian J Med Res. 2011;134:389-91.

United States Centers for Disease Control and Prevention. Interim guidance on case definitions to be used for investigations of novel influenza A (H1N1) cases. Available at: Accessed 2 June 2009.

Guha S, Munjal YP, Agarwal SS, Parikh KK, Jha V, Muruganathan A, et al. Recommendations for vaccination against seasonal influenza in adult high risk groups: South Asian Recommendations. J Assoc Physicians India. 2016;64(7Suppl):3-11.

WHO Guidelines for Pharmacological Management of Pandemic Influenza A (H1N1) 2009 and Other Influenza Viruses. Available at: Accessed March 1, 2015.