Influenza Differential Diagnoses

Sections

Influenza

DDx

Diagnostic Considerations

Accurately diagnosing influenza A or B infection solely on the basis of clinical criteria is difficult because of the overlapping symptoms caused by the various viruses associated with upper respiratory tract infection (URI). Viruses that may initially cause influenzalike symptoms include adenoviruses, enteroviruses, and paramyxoviruses.

The early presentation of mild or moderate cases of flavivirus infections (eg, dengue) may initially mimic influenza. For example, some cases of West Nile fever acquired in New York in 1999 were clinically misdiagnosed as influenza.^[3]

Like influenza, URIs from these viruses are more common in the winter. As a result, during the winter, clinics and emergency department waiting rooms fill with patients who have influenza or other URIs.

Influenza pneumonia must be differentiated from other forms of viral pneumonia, bacterial pneumonia, and noninfectious causes of respiratory distress, such as heart failure, chronic obstructive pulmonary disease, pulmonary edema, and aspiration pneumonitis.

H5N1 avian influenza

Risk factors or features that should raise the index of suspicion of H5N1 avian influenza include the following^[36]:

Recent (within the preceding 2 weeks) travel to or location in a country with known avian influenza cases in animals or humans
Unusual comorbidities such as encephalopathy or diarrhea
History of exposure to birds, especially living in close proximity to birds, contact with sick or dying birds, or consumption of incompletely cooked bird meat
History of exposure to individuals with known avian influenza, especially family, or to sick people in a country with known human cases of avian influenza

The situation can be complicated during outbreaks of severe respiratory disease other than avian influenza. The first case of laboratory-confirmed avian influenza infection was documented during the severe acute respiratory syndrome (SARS) outbreak of 2002-2003 and was mistakenly misdiagnosed as SARS.^[37]

Cases of avian influenza in which respiratory disease was limited or not apparent (with even normal chest radiography findings) have been described, though they account for only a small percentage of cases overall.^[36]The primary presenting illness has been encephalitis or diarrhea.

Differential Diagnoses

Workup

Centers for Disease Control and Prevention. Key Facts About Seasonal Influenza (Flu). Centers for Disease Control and Prevention. Available at http://www.cdc.gov/flu/keyfacts.htm. Accessed: March 11, 2013.
Gu Y, Komiya N, Kamiya H, Yasui Y, Taniguchi K, Okabe N. Pandemic (H1N1) 2009 transmission during presymptomatic phase, Japan. Emerg Infect Dis. 2011 Sep. 17(9):1737-9. [Medline]. [Full Text].
Guharoy R, Gilroy SA, Noviasky JA, Ference J. West Nile virus infection. Am J Health Syst Pharm. 2004 Jun 15. 61(12):1235-41. [Medline].
Jefferson T, Di Pietrantonj C, Rivetti A, Bawazeer GA, Al-Ansary LA, Ferroni E. Vaccines for preventing influenza in healthy adults. Cochrane Database Syst Rev. 2010 Jul 7. CD001269. [Medline].
Brooks M. FDA Okays 4-Strain Seasonal Influenza Vaccine. Medscape Medical News. December 17, 2012. Available at http://www.medscape.com/viewarticle/776271?src=nl_newsalert. Accessed: March 5, 2013.
FDA approves first quadrivalent vaccine to prevent seasonal influenza. US Food & Drug Administration, February 29, 2012. Available at http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm294057.htm. Accessed: March 11, 2013.
FDA Approves First U.S. Vaccine for Humans Against the Avian Influenza Virus H5N1. Center for Disease Control and Prevention. Available at http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/2007/ucm108892.htm. Accessed: March 11, 2013.
[Guideline] Grohskopf LA, Sokolow LZ, Broder KR, Walter EB, Fry AM, Jernigan DB. Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices-United States, 2018-19 Influenza Season. MMWR Recomm Rep. 2018 Aug 24. 67 (3):1-20. [Medline]. [Full Text].
Flu Vaccine and People with Egg Allergies. Centers for Disease Control and Prevention (CDC). Available at https://www.cdc.gov/flu/protect/vaccine/egg-allergies.htm. 2016 Sep 2; Accessed: August 16, 2017.
Lee V, Yap J, Cook AR, et al. Effectiveness of public health measures in mitigating pandemic influenza spread: a prospective sero-epidemiological cohort study. J Infect Dis. 2010 Nov 1. 202 (9):1319-26. [Medline].
Kilbourne ED. Influenza pandemics of the 20th century. Emerg Infect Dis. 2006 Jan. 12(1):9-14. [Medline]. [Full Text].
Seasonal Influenza (Flu): Guidance for Clinicians on the Use of RT-PCR and Other Molecular Assays for Diagnosis of Influenza Virus Infection. Centers for Disease Control and Prevention. Available at http://www.cdc.gov/flu/professionals/diagnosis/molecular-assays.htm. Accessed: March 13, 2013.
Gubareva LV, Kaiser L, Hayden FG. Influenza virus neuraminidase inhibitors. Lancet. 2000 Mar 4. 355(9206):827-35. [Medline].
Drake JW. Rates of spontaneous mutation among RNA viruses. Proc Natl Acad Sci U S A. 1993 May 1. 90(9):4171-5. [Medline]. [Full Text].
Avian influenza ("bird flu"): fact sheet. World Health Organization. Available at http://www.who.int/mediacentre/factsheets/avian_influenza/en/print.html. Accessed: August 14, 2012.
World Health Organization Writing Group, Bell D, Nicoll A, et al. Non-pharmaceutical interventions for pandemic influenza, international measures. Emerg Infect Dis. 2006 Jan. 12 (1):81-7. [Medline]. [Full Text].
Auewarakul P, Suptawiwat O, Kongchanagul A, et al. An avian influenza H5N1 virus that binds to a human-type receptor. J Virol. 2007 Sep. 81(18):9950-5. [Medline]. [Full Text].
World Health Organization. Cumulative number of confirmed human cases of avian influenza A/(H5N1) reported to WHO. World Health Organization. Available at http://www.who.int/influenza/human_animal_interface/EN_GIP_20120810CumulativeNumberH5N1cases.pdf. Accessed: August 13, 2012.
Matsuzaki Y, Abiko C, Mizuta K, et al. A nationwide epidemic of influenza C virus infection in Japan in 2004. J Clin Microbiol. 2007 Mar. 45(3):783-8. [Medline]. [Full Text].
Update: influenza activity - United States, 2011-12 season and composition of the 2012-13 influenza vaccine. MMWR Morb Mortal Wkly Rep. 2012 Jun 8. 61(22):414-20. [Medline].
Influenza (Seasonal) World Health Organization. Available at http://www.who.int/mediacentre/factsheets/fs211/en. Accessed: August 13, 2012.
2012-2013 Influenza Season Week 9 ending March 2, 2013. Centers for Disease Control and Prevention. Available at http://www.cdc.gov/flu/weekly/. Accessed: March 11, 2013.
Centers for Disease Control and Prevention. Seasonal Influenza: 2009-2010 Influenza (Flu) Season. Available at http://www.cdc.gov/flu/about/season/current-season.htm. Accessed: August 19, 2012.
Centers for Disease Control and Prevention. Avian Influenza A Virus Infections in Humans. Available at http://www.cdc.gov/flu/avianflu/avian-in-humans.htm. Accessed: August 14, 2012.
Wang TT, Parides MK, Palese P. Seroevidence for H5N1 influenza infections in humans: meta-analysis. Science. 2012 Mar 23. 335 (6075):1463. [Medline].
Lau D, Eurich D, Majumdar S, Katz A, Johnson J. Working-age adults with diabetes experience greatersusceptibility to seasonal influenza: a population-based cohort study. Diabetologia- Springer Link. Available at http://link.springer.com/article/10.1007/s00125-013-3158-8#. Accessed: February 3, 2014.
Melville N. New Evidence: Diabetes Does Up Risk for Flu-Related Illness. Medscape [serial online]. Available at http://www.medscape.com/viewarticle/819737. Accessed: February 3, 2014.
Early Reports of pH1N1-Associated Illnesses: Alert for New Hampshire Clinicians. Medscape. Dec 26 2013. [Full Text].
Health Alert Network. Notice to Clinicians: Early Reports of pH1N1-Associated Illnesses for the 2013-14 Influenza Season. Centers for Disease Control and Prevention. Dec 24 2013. [Full Text].
Steininger C, Popow-Kraupp T, Laferl H, et al. Acute encephalopathy associated with influenza A virus infection. Clin Infect Dis. 2003 Mar 1. 36(5):567-74. [Medline].
Chertow DS, Memoli MJ. Bacterial coinfection in influenza: a grand rounds review. JAMA. 2013 Jan 16. 309(3):275-82. [Medline].
Tasher D, Stein M, Simoes EA, Shohat T, Bromberg M, Somekh E. Invasive bacterial infections in relation to influenza outbreaks, 2006-2010. Clin Infect Dis. 2011 Dec. 53 (12):1199-207. [Medline].
Kumar K, Guirgis M, Zieroth S, et al. Influenza myocarditis and myositis: case presentation and review of the literature. Can J Cardiol. 2011 Jul-Aug. 27(4):514-22. [Medline].
Apisarnthanarak A, Erb S, Stephenson I, et al. Seroprevalence of anti-H5 antibody among Thai health care workers after exposure to avian influenza (H5N1) in a tertiary care center. Clin Infect Dis. 2005 Jan 15. 40(2):e16-8. [Medline].
[Guideline] Interim Guidance for Laboratory Testing of Persons with Suspected Infection with Highly Pathogenic Avian Influenza A (H5N1) Virus in the United States. Center for Disease Control and Prevention. Available at http://www.cdc.gov/flu/avianflu/guidance-labtesting.htm. Accessed: August 15, 2012.
[Guideline] Clinical management of human infection with avian influenza A (H5N1) virus. World Health Organization. Available at http://www.who.int/influenza/resources/documents/ClinicalManagement07.pdf.
World Health Organization. H5N1 avian influenza: Timeline of major events. World Health Organization. Available at http://www.who.int/csr/disease/avian_influenza/Timeline_2007_03_20.pdf. Accessed: March 15, 2011.
U.S. Food and Drug Administration. Performance and Cautions in Using Rapid Influenza Virus Diagnostic Tests. Available at http://www.fda.gov/MedicalDevices/Safety/AlertsandNotices/TipsandArticlesonDeviceSafety/ucm109432.htm%20. Accessed: August 19, 2012.
Chartrand C, Leeflang MM, Minion J, Brewer T, Pai M. Accuracy of rapid influenza diagnostic tests: a meta-analysis. Ann Intern Med. 2012 Apr 3. 156(7):500-11. [Medline].
Landry ML. Diagnostic tests for influenza infection. Curr Opin Pediatr. 2011 Feb. 23(1):91-7. [Medline].
Lowes R. New Flu Test Delivers Molecular Results in Under 15 Minutes. Medscape Medical News. Available at http://www.medscape.com/viewarticle/826847. Accessed: June 20, 2014.
Alere Inc. Alere receives FDA clearance for Alere i influenza A and B test [press release]. June 16, 2014. Available at http://news.alere.com/~/media/Files/A/Alere-Newsroom/press-release/Alere_i_US_release_6_16_2014.pdf. Accessed: July 16, 2013.
Haran JP, Buglione-Corbett R, Lu S. Cytokine markers as predictors of type of respiratory infection in patients during the influenza season. Am J Emerg Med. 2013 May. 31(5):816-21. [Medline].
Oner AF, Bay A, Arslan S, et al. Avian influenza A (H5N1) infection in eastern Turkey in 2006. N Engl J Med. 2006 Nov 23. 355(21):2179-85. [Medline].
FDA Clears Rapid Test for Avian Influenza A Virus in Humans. Center for Disease Control and Prevention. Available at http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm149557.htm. Accessed: August 19, 2012.
Beigel JH, Farrar J, Han AM, et al. Avian influenza A (H5N1) infection in humans. N Engl J Med. 2005 Sep 29. 353(13):1374-85. [Medline].
Chotpitayasunondh T, Ungchusak K, Hanshaoworakul W, et al. Human disease from influenza A (H5N1), Thailand, 2004. Emerg Infect Dis. 2005 Feb. 11(2):201-9. [Medline]. [Full Text].
Brown T. CDC Releases New H7N9 Testing Recommendations. Medscape [serial online]. Available at http://www.medscape.com/viewarticle/805620. Accessed: July 22, 2013.
CDC. Human Infections with Avian Influenza A (H7N9) Viruses. Centers for Disease Control and Prevention (CDC). Available at http://www.bt.cdc.gov/HAN/han00347.asp. Accessed: July 22, 2013.
Preventing Seasonal Flu With Vaccination. Centers for Disease Control and Prevention. Available at http://www.cdc.gov/flu/protect/vaccine/. Accessed: August 17, 2012.
[Guideline] Robinson CL, Romero JR, Kempe A, Pellegrini C, Szilagyi P. Advisory Committee on Immunization Practices Recommended Immunization Schedule for Children and Adolescents Aged 18 Years or Younger - United States, 2018. MMWR Morb Mortal Wkly Rep. 2018 Feb 9. 67 (5):156-157. [Medline]. [Full Text].
Grohskopf LA, Sokolow LZ, Broder KR, Walter EB, Bresee JS, et al. Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices — United States, 2017–18 Influenza Season. MMWR Morb Mortal Wkly Rep. 2017 Aug 25. 66(2):1-20. [Full Text].
Troy Brown, RN. FDA Committee Recommends 2018-2019 Influenza Vaccine Strains. Medscape Medical News. 2018 Mar 01. Available at https://www.medscape.com/viewarticle/893314.
Recommended Immunization Schedules for Adults. Centers for Disease Control and Prevention (CDC). Available at https://www.cdc.gov/vaccines/schedules/hcp/adult.html. 2017 Feb 27; Accessed: August 16, 2017.
Troy Brown, RN. Nasal Flu Vaccine Back on CDC List of Recommended Vaccines. Medscape Medical News. 2018 Feb 22. Available at https://www.medscape.com/viewarticle/892970.
Carr S, Allison KJ, Van De Velde LA, et al. Safety and immunogenicity of live attenuated and inactivated influenza vaccines in children with cancer. J Infect Dis. 2011 Nov 15. 204 (10):1475-82. [Medline].
Jackson ML, Chung JR, Jackson LA, Phillips CH, Benoit J, Monto AS, et al. Influenza Vaccine Effectiveness in the United States during the 2015-2016 Season. N Engl J Med. 2017 Aug 10. 377 (6):534-543. [Medline].
ACIP votes down use of LAIV for 2016-2017 flu season. Centers for Disease Control and Prevention (CDC) press release. 2016 Jun 22. Available at http://www.cdc.gov/media/releases/2016/s0622-laiv-flu.html.
FDA approves first seasonal influenza vaccine manufactured using cell culture technology. US Food & Drug Administration. November 20, 2012. Available at http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm328982.htm. Accessed: March 5, 2013.
Stobbe M. New flu vaccine only a little better than traditional shot. ABC News. June 20, 2018. Available at https://abcnews.go.com/Health/wireStory/flu-vaccine-works-traditional-shot-56033657.
Lowes R. FDA Okays Novel Flu Vaccine Made Without Eggs, Viruses. Medscape Medical News. Jan 16 2013. Available at http://www.medscape.com/viewarticle/777773. Accessed: January 29, 2013.
FDA. FDA Approves New Seasonal Influenza Vaccine Made Using Novel Technology. US Food and Drug Administration. Jan 16 2013. Available at http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm335891.htm. Accessed: Jan 28 2013.
Maternal and Infant Outcomes Among Severely Ill Pregnant and Postpartum Women with 2009 Pandemic Influenza A (H1N1) --- United States, April 2009--August 2010. MMWR Morb Mortal Wkly Rep. Sep 9 2011;60:1193-6. [Medline]. [Full Text].
Benowitz I, Esposito DB, Gracey KD, Shapiro ED, Vazquez M. Influenza vaccine given to pregnant women reduces hospitalization due to influenza in their infants. Clin Infect Dis. 2010 Dec 15. 51 (12):1355-61. [Medline].
Brooks M. Trivalent Flu Vaccine Works in Pregnant Women. Medscape. Dec 13 2013. [Full Text].
Thompson MG, Li DK, Shifflett P, et al. Effectiveness of seasonal trivalent influenza vaccine for preventing influenza virus illness among pregnant women: a population-based case-control study during the 2010-2011 and 2011-2012 influenza seasons. Clin Infect Dis. 2013 Nov 26. [Medline].
Influenza vaccination coverage among pregnant women--United States, 2012-13 influenza season. MMWR Morb Mortal Wkly Rep. 2013 Sep 27. 62(38):787-92. [Medline]. [Full Text].
Falsey AR, Treanor JJ, Tornieporth N, Capellan J, Gorse GJ. Randomized, double-blind controlled phase 3 trial comparing the immunogenicity of high-dose and standard-dose influenza vaccine in adults 65 years of age and older. J Infect Dis. 2009 Jul 15. 200 (2):172-80. [Medline].
DiazGranados CA, Dunning AJ, Kimmel M, et al. Efficacy of high-dose versus standard-dose influenza vaccine in older adults. N Engl J Med. 2014 Aug 14. 371(7):635-45. [Medline].
Garcia J. Influenza: high-dose vaccine decreases flu in older adults. Medscape Medical News. August 14, 2014. [Full Text].
Woods JA, Keylock KT, Lowder T, et al. Cardiovascular exercise training extends influenza vaccine seroprotection in sedentary older adults: the immune function intervention trial. J Am Geriatr Soc. 2009 Dec. 57 (12):2183-91. [Medline].
Alsharifi M, Furuya Y, Bowden TR, et al. Intranasal flu vaccine protective against seasonal and H5N1 avian influenza infections. PLoS One. 2009. 4 (4):e5336. [Medline].
MacMahon KL, Delaney LJ, Kullman G, Gibbins JD, Decker J, Kiefer MJ. Protecting poultry workers from exposure to avian influenza viruses. Public Health Rep. 2008 May-Jun. 123(3):316-22. [Medline]. [Full Text].
Gray GC, Baker WS. The importance of including swine and poultry workers in influenza vaccination programs. Clin Pharmacol Ther. 2007 Dec. 82 (6):638-41. [Medline].
H5N1 Influenza Virus Vaccine Questions and Answers. US Food and Drug Administration. Available at http://www.fda.gov/BiologicsBloodVaccines/Vaccines/QuestionsaboutVaccines/ucm080753.htm. Accessed: August 19, 2012.
Belshe RB, Frey SE, Graham I, et al. Safety and immunogenicity of influenza A H5 subunit vaccines: effect of vaccine schedule and antigenic variant. J Infect Dis. 2011 Mar 1. 203(5):666-73. [Medline]. [Full Text].
Availability of a new recombinant H5N1 vaccine virus. World Health Organization. Available at http://www.who.int/influenza/vaccines/virus/h5n1virus09march/en/index.html. Accessed: August 19, 2012.
FDA. FDA approves first adjuvanted vaccine for prevention of H5N1 avian influenza. Nov 22 2013. [Full Text].
Lowes R. FDA Approves First Adjuvanted Vaccine for H5N1 Bird Flu. Medscape Medical News. Nov 22 2013. [Full Text].
Gensheimer KF, Meltzer MI, Postema AS, Strikas RA. Influenza pandemic preparedness. Emerg Infect Dis. 2003 Dec. 9(12):1645-8. [Medline]. [Full Text].
Centers for Disease Control and Prevention. Seasonal Influenza (Flu): Preventing the Flu: Good Health Habits Can Help Stop Germs. Available at http://www.cdc.gov/flu/protect/habits.htm. Accessed: May 7, 2013.
Kohno S, Kida H, Mizuguchi M, Shimada J, S-021812 Clinical Study Group. Efficacy and safety of intravenous peramivir for treatment of seasonal influenza virus infection. Antimicrob Agents Chemother. 2010 Nov. 54 (11):4568-74. [Medline]. [Full Text].
Adisasmito W, Chan PK, Lee N, et al. Effectiveness of antiviral treatment in human influenza A(H5N1) infections: analysis of a Global Patient Registry. J Infect Dis. 2010 Oct 15. 202 (8):1154-60. [Medline].
Muthuri SG, Myles PR, Venkatesan S, Leonardi-Bee J, Nguyen-Van-Tam JS. Impact of neuraminidase inhibitor treatment on outcomes of public health importance during the 2009-2010 influenza A(H1N1) pandemic: a systematic review and meta-analysis in hospitalized patients. J Infect Dis. 2013 Feb 15. 207(4):553-63. [Medline]. [Full Text].
Lam J, Nikhanj N, Ngab T, et al. Severe cases of pandemic H1N1 pneumonia and respiratory failure requiring intensive care. J Intensive Care Med. 2011 Sep-Oct. 26 (5):318-25. [Medline].
Centers for Disease Control and Prevention. Seasonal Influenza (Flu): Antiviral Drugs. Available at http://www.cdc.gov/flu/professionals/antivirals/index.htm. Accessed: May 7, 2013.
Hayden FG, Sugaya N, Hirotsu N, Lee N, de Jong MD, Hurt AC, et al. Baloxavir Marboxil for Uncomplicated Influenza in Adults and Adolescents. N Engl J Med. 2018 Sep 6. 379 (10):913-923. [Medline].
Hayden FG, Atmar RL, Schilling M, et al. Use of the selective oral neuraminidase inhibitor oseltamivir to prevent influenza. N Engl J Med. 1999 Oct 28. 341 (18):1336-43. [Medline].
Aoki FY, Macleod MD, Paggiaro P, et al; IMPACT Study Group. Early administration of oral oseltamivir increases the benefits of influenza treatment. J Antimicrob Chemother. 2003 Jan. 51 (1):123-9. [Medline].
Hill G, Cihlar T, Oo C, et al. The anti-influenza drug oseltamivir exhibits low potential to induce pharmacokinetic drug interactions via renal secretion-correlation of in vivo and in vitro studies. Drug Metab Dispos. 2002 Jan. 30 (1):13-9. [Medline].
Hayden FG, Treanor JJ, Fritz RS, et al. Use of the oral neuraminidase inhibitor oseltamivir in experimental human influenza: randomized controlled trials for prevention and treatment. JAMA. 1999 Oct 6. 282 (13):1240-6. [Medline].
Treanor JJ, Hayden FG, Vrooman PS, et al. Efficacy and safety of the oral neuraminidase inhibitor oseltamivir in treating acute influenza: a randomized controlled trial. US Oral Neuraminidase Study Group. JAMA. 2000 Feb 23. 283 (8):1016-24. [Medline].
Heinonen S, Silvennoinen H, Lehtinen P, et al. Early oseltamivir treatment of influenza in children 1-3 years of age: a randomized controlled trial. Clin Infect Dis. 2010 Oct 15. 51 (8):887-94. [Medline].
Jefferson T, Jones MA, Doshi P, et al. Neuraminidase inhibitors for preventing and treating influenza in healthy adults and children. Cochrane Database Syst Rev. 2012 Jan 18. 1:CD008965. [Medline].
Hayden FG, Gubareva LV, Monto AS, et al; Zanamivir Family Study Group. Inhaled zanamivir for the prevention of influenza in families. Zanamivir Family Study Group. N Engl J Med. 2000 Nov 2. 343 (18):1282-9. [Medline].
Randomised trial of efficacy and safety of inhaled zanamivir in treatment of influenza A and B virus infections. The MIST (Management of Influenza in the Southern Hemisphere Trialists) Study Group. Lancet. 1998 Dec 12. 352 (9144):1877-81. [Medline].
Chamni S, De-Eknamkul W. Recent progress and challenges in the discovery of new neuraminidase inhibitors. Expert Opin Ther Pat. 2013 Apr. 23(4):409-23. [Medline].
Watanabe A, Chang SC, Kim MJ, Chu DW, Ohashi Y, MARVEL Study Group. Long-acting neuraminidase inhibitor laninamivir octanoate versus oseltamivir for treatment of influenza: A double-blind, randomized, noninferiority clinical trial. Clin Infect Dis. 2010 Nov 15. 51 (10):1167-75. [Medline].
Grohskopf L. 2017-2018 Influenza Vaccination Recommendations. Medscape Perspective. CDC Expert Commentary. Available at http://www.medscape.com/viewarticle/885567. September 20, 2017; Accessed: October 12, 2017.
[Guideline] Grohskopf LA, Sokolow LZ, Broder KR, Walter EB, Bresee JS, Fry AM, et al. Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices - United States, 2017-18 Influenza Season. MMWR Recomm Rep. 2017 Aug 25. 66 (2):1-20. [Medline].
Brown T. AAP Recommends Flu Vaccine for All Kids Older Than 6 Months. Medscape News. Available at http://www.medscape.com/viewarticle/885217. September 05, 2017; Accessed: October 12, 2017.
Ault A. CDC Says Influenza Activity as Widespread as 2009 Pandemic. Medscape Medical News. Available at https://www.medscape.com/viewarticle/891870. January 26, 2018; Accessed: January 30, 2018.
Brooks M. US Influenza Activity Widespread and Intense, May Be Peaking. Medscape Medical News. Available at https://www.medscape.com/viewarticle/891265. January 12, 2018; Accessed: January 16, 2018.
Hung IF, Leung AY, Chu DW, et al. Prevention of acute myocardial infarction and stroke among elderly persons by dual pneumococcal and influenza vaccination: a prospective cohort study. Clin Infect Dis. 2010 Nov 1. 51 (9):1007-16. [Medline].
Christenson B, Pauksen K, Sylvan SP. Effect of influenza and pneumococcal vaccines in elderly persons in years of low influenza activity. Virol J. 2008 Apr 28. 5:52. [Medline]. [Full Text].

Media Gallery

Countries where avian influenza has been reported. Image courtesy of the World Health Organization.
Colorized transmission electron micrograph shows avian influenza A H5N1 viruses (gold) grown in MDCK cells (green). Image courtesy of Centers for Disease Control and Prevention.
Transmission electron micrograph (original magnification 150,000X) shows ultrastructural details of an avian influenza A (H5N1) virion, a subtype of avian influenza A. Note the stippled appearance of the roughened surface of the proteinaceous coat encasing the virion. Image courtesy of Centers for Disease Control and Prevention.

of 3

Author

Hien H Nguyen, MD, MS Chief of Infectious Diseases, VA Northern California Health Care System; Clinical Professor, Division of Infectious Diseases and Pulmonary/Critical Care Medicine, Infectious Diseases Consultant and Hospitalist, University of California, Davis, Health System; Medical Director, Acute Infections Management Service, Antimicrobial Infusion Service

Hien H Nguyen, MD, MS is a member of the following medical societies: American College of Physicians, Infectious Diseases Society of America, Society of Critical Care Medicine

Disclosure: Nothing to disclose.

Coauthor(s)

Robert W Derlet, MD Professor of Emergency Medicine, University of California at Davis School of Medicine; Chief Emeritus, Emergency Department, University of California at Davis Health System

Robert W Derlet, MD is a member of the following medical societies: American Academy of Emergency Medicine, American Association for the Advancement of Science, Infectious Diseases Society of America, Society for Academic Emergency Medicine, Wilderness Medical Society

Disclosure: Nothing to disclose.

Christian E Sandrock, MD, MPH, FCCP Associate Professor of Clinical Medicine, Division of Pulmonary/Critical Care Medicine, Division of Infectious Diseases, Department of Internal Medicine, University of California, Davis Medical Center

Christian E Sandrock, MD, MPH, FCCP is a member of the following medical societies: American College of Chest Physicians, American Thoracic Society, Infectious Diseases Society of America

Disclosure: Received honoraria from Pfizer for speaking and teaching; Received honoraria from Pfizer for consulting; Received honoraria from therevance for consulting; Received honoraria from GSK for speaking and teaching.

Specialty Editor Board

Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.

Chief Editor

Michael Stuart Bronze, MD David Ross Boyd Professor and Chairman, Department of Medicine, Stewart G Wolf Endowed Chair in Internal Medicine, Department of Medicine, University of Oklahoma Health Science Center; Master of the American College of Physicians; Fellow, Infectious Diseases Society of America

Michael Stuart Bronze, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Physicians, American Medical Association, Association of Professors of Medicine, Infectious Diseases Society of America, Oklahoma State Medical Association, Southern Society for Clinical Investigation

Disclosure: Nothing to disclose.

Acknowledgements

Nicholas John Bennett, MB, BCh, PhD, Assistant Professor in Pediatrics, Division of Infectious Diseases, Connecticut Children's Medical Center

Nicholas John Bennett, MB, BCh, PhD, is a member of the following medical societies: Alpha Omega Alpha and American Academy of Pediatrics