What are the causes of recurrent influenza (flu)?

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Last updated: April 29, 2025View editorial policy

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From the Guidelines

Recurrent flu can be effectively managed with a combination of preventive measures and prompt treatment, and I strongly recommend getting an annual flu vaccine, which is the most effective way to prevent influenza infection, as supported by the CDC guidelines 1. To manage recurrent flu, consider the following:

  • Get an annual flu vaccine to prevent influenza infection
  • Practice good hygiene by washing hands frequently with soap and water for at least 20 seconds, avoiding close contact with sick individuals, and disinfecting commonly touched surfaces
  • Boost your immune system through adequate sleep (7-9 hours nightly), regular exercise, stress management, and a balanced diet rich in fruits and vegetables
  • If you have underlying health conditions like asthma or diabetes, ensure they're well-controlled as they can increase susceptibility to flu complications
  • Consider antiviral medications like oseltamivir (Tamiflu) 75mg twice daily for 5 days when symptoms first appear, ideally within 48 hours of onset, as recommended by the CDC for high-risk individuals 1
  • Recurrent flu may indicate an underlying immune system issue, so consult a healthcare provider if you experience more than two flu episodes in a single season The flu virus constantly mutates, which explains why you can get infected multiple times with different strains, and why annual vaccination with updated formulations is necessary for optimal protection, as highlighted in the study on influenza epidemiology 1.

From the Research

Recurrent Flu Treatment and Prevention

  • Influenza vaccination can reduce illness in 75%-80% of healthy adults, and is recommended for individuals with chronic underlying diseases and those aged 65 years or older 2.
  • Antiviral agents such as amantadine, rimantadine, zanamivir, and oseltamivir can modify the severity of illness and reduce the duration of illness by about 1.5-2.5 days 2, 3.
  • Neuraminidase inhibitors like zanamivir and oseltamivir are effective against both influenza A and B, and can decrease the median duration of influenza-related symptoms by approximately 1 day if initiated within 48 hours of symptom onset 3, 4.

Antiviral Resistance

  • Resistance to antiviral drugs can occur due to mutations within the therapeutic target proteins, and has been detected in various influenza viruses, including A(H1N1) and A(H3N2) 5.
  • The prevalence of oseltamivir-resistant seasonal A(H1N1) viruses increased rapidly in 2007/2008, and nearly all viruses circulating during the following seasons were resistant to oseltamivir 5.
  • Only neuraminidase inhibitors are recommended for influenza treatment today, due to the high prevalence of resistance to adamantane derivatives 5.

Innate Immune Responses

  • The innate immune system plays a crucial role in limiting influenza virus replication and activating the adaptive immune system, but an overzealous response can lead to immunopathology and secondary bacterial infections 6.
  • The mechanisms utilized by the innate immune system to limit influenza virus replication, and the damage caused by influenza viruses on respiratory tissues, are complex and multifaceted 6.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

The treatment of influenza with antiviral drugs.

CMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne, 2003

Research

Antiviral agents for treating influenza.

Cleveland Clinic journal of medicine, 2000

Research

Influenza viruses - antiviral therapy and resistance.

GMS infectious diseases, 2017

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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