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Influenza infection

Last reviewed: 18 Jun 2025
Last updated: 19 Feb 2025

Summary

Definition

History and exam

Key diagnostic factors

  • winter season
  • current influenza outbreak
  • unvaccinated
  • fever with cough
Full details

Other diagnostic factors

  • sore throat
  • cervical lymphadenopathy
  • dyspnea
Full details

Risk factors

  • age ≥65 years
  • age 6-59 months
  • chronic cardiovascular or respiratory conditions
  • diabetes
  • hemoglobinopathy
  • immunocompromised status
  • chronic kidney disease (CKD)
  • pregnancy
  • caregivers and household contacts of high-risk groups
  • healthcare workers
Full details

Diagnostic tests

1st tests to order

  • clinical diagnosis
Full details

Tests to avoid

  • broad respiratory pathogen panels
  • serology
Full details

Tests to consider

  • molecular assays
  • antigen detection tests
  • viral culture
  • chest x-ray
Full details

Treatment algorithm

INITIAL

exposure to infected individual(s) in at-risk population

ACUTE

adults

children

Contributors

Authors

Kyle Eggleton, MBChB PhD FRNZCGP(Dist)

Associate Dean Rural

Department of General Practice and Primary Health Care

University of Auckland

Auckland

New Zealand

Disclosures

KE declares that he has no competing interests.

Rachel Roskvist, MBChB, FRNZCGP, MHSc

Senior Lecturer

Department of General Practice and Primary Health Care

University of Auckland

Auckland

New Zealand

Declarações

RR declares that she has no competing interests.

Bruce Arroll, MBChB PhD FRNZCGP

Department of General Practice and Primary Health Care

University of Auckland

Auckland

New Zealand

Declarações

BA declares that he has no competing interests.

Agradecimentos

Dr Kyle Eggleton, Dr Rachel Roskvist, and Professor Bruce Arroll would like to gratefully acknowledge Dr Cristine Radojicic, a previous contributor to this topic.

Declarações

CR declares that she is on Advisory boards for CSL Behring and Speakers Bureau Biocryst.

Revisores

Waleed Javaid, MD, FACP, FIDSA

Associate Professor

Medical Director of Infection Control

Infectious Disease

Department of Medicine

SUNY Upstate Medical University

Syracuse

NY

Declarações

WJ declares that he has no competing interests.

Rachel L. Miller, MD, FAAAAI

Associate Professor of Clinical Medicine and Environmental Health Sciences

Columbia University College of Physicians and Surgeons

New York

NY

Declarações

RLM declares that she has no competing interests.

Mark Sands, MD, FAAAAI

Chief

SUNY Buffalo School of Medicine

Division Allergy and Immunology

Buffalo

NY

Declarações

MS declares that he has no competing interests.

An De Sutter, MD, PhD

Associate Professor

Department of General Practice and Primary Health Care

Ghent University

Ghent

Belgium

Declarações

ADS declares that she has no competing interests.

Referências

Nossas equipes internas de editoria e de evidências trabalham em conjunto com colaboradores internacionais especializados e pares revisores para garantir que forneçamos acesso às informações o mais clinicamente relevantes possível.

Principais artigos

Uyeki TM, Bernstein HH, Bradley JS, et al. Clinical practice guidelines by the Infectious Diseases Society of America: 2018 update on diagnosis, treatment, chemoprophylaxis, and institutional outbreak management of seasonal influenza. Clin Infect Dis. 2019 Mar 5;68(6):e1-47.Texto completo  Resumo

Centers for Disease Control and Prevention. Influenza (flu). Feb 2024 [internet publication].Texto completo

Centers for Disease Control and Prevention. Morbidity and Mortality Weekly Report (MMWR): prevention and control of seasonal influenza with vaccines: recommendations of the advisory committee on immunization practices — United States, 2023–24 Influenza Season. Aug 2023. [internet publication].Texto completo

Centers for Disease Control and Prevention. Child and adolescent immunization schedule: recommendations for ages 18 years or younger, United States, 2024. Nov 2023 [internet publication].Texto completo

Centers for Disease Control and Prevention. Adult immunization schedule by age: recommendations for ages 19 years or older, United States, 2024. Nov 2023 [internet publication].Texto completo

Centers for Disease Control and Prevention. Influenza antiviral medications: summary for clinicians. Dec 2023 [internet publication].Texto completo

Artigos de referência

Uma lista completa das fontes referenciadas neste tópico está disponível para os usuários com acesso total ao BMJ Best Practice.
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  • Diretrizes

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    • Canadian immunization guide chapter on influenza and statement on seasonal influenza vaccine for 2022-2023
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