Influenza

Essential Evidence

Last Updated on 2022-06-24 © 2022 John Wiley & Sons, Inc.

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Authors:
Mark H. Ebell, MD, MS, Professor, College of Public Health, University of Georgia

Editors:
Randall Forsch, MD, MPH, Assistant Professor, University of Michigan
Mark H. Ebell, MD, MS, Professor, College of Public Health, University of Georgia
Kenny Lin, MD, MPH, Professor of Family Medicine, Georgetown University

Overall Bottom Line

  • Yearly influenza vaccination is recommended by ACIP (US) for persons over the age of 6 months. A
  • Patients classically present with rapid onset of fever, cough, chills or rigors, sore throat, and myalgias. A clinical decision rule can be used to identify patients at low, moderate or high risk of influenza. B
  • Rapid antigen tests are most useful during the beginning and end of the flu season. C
  • Treatment is largely supportive; antiviral medications are recommended only if the likelihood of influenza is high and the patient presents within 24 hours of symptom onset. There is no evidence that they reduce serious complications or hospitalization. A
  • Predictors of adverse outcome in the elderly include increased age, previous hospitalization, comorbidities, gender, and number of outpatient visits in the previous year (Table 1). A

Management of Special Populations

The Elderly

  • Oseltamivir provided very little benefit as prophylaxis for older patients who had received influenza vaccine. 38

Infants and Children

  • Likelihood of hospitalization for flu was 7 per 10,000 child-years in an urban cohort. A history of cardiac and neuromuscular conditions was an independent predictor for hospitalization. Median age of hospitalization was 1.8 years. 9
  • Oseltamivir is approved for children over age 1 year. Dosing is 75 mg bid if >40 kg or 13 years old, 60 mg bid if 23 to 40 kg, 45 mg bid if 15 to 23 kg, and 30 mg bid if ≤5 kg.
  • Zanamivir is approved for children aged 7 years and older is 10 mg by metered-dose inhaler twice daily.
  • Rimantadine is not FDA approved for treatment of influenza in children.