Influenza

Essential Evidence

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

Printer Friendly

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

Prognosis

Bottom Line

  • In a case-control study of 119 hospitalized patients and 196 matched controls, risk factors for hospitalization included COPD, more than one significant comorbidty, polypharmacy, more than 5 GP consultations in the previous year, and previous hospitalizations in patients aged 18 to 64 years. B 11
  • In the same study, risk factors for patients over age 65 years were all of the above plus CHF and minus previous hospitalizations. B 11
  • A clinical decision rule was developed in 16,280 patients and validated in over 11,000 patients to predict the likelihood of hospitalization or pneumonia or death from any cause during flu season in community-dwelling elderly (aged 65 years and older). Key factors include age, previous hospitalization, comorbidities, gender, and number of outpatient visits in the previous year (Table 1). A 10