Influenza vaccine safety

Adverse reactions following vaccination

Risks of an adverse event following influenza vaccination are far less common than complications related to influenza itself, and the adverse events are generally localized and mild. Adverse reactions are more common in children not previously exposed to the vaccine or virus than in adults. The benefits of vaccination substantially outweigh the risks. 

Table 2: Comparison of risks associated with influenza disease and inactivated seasonal influenza vaccination

Risks associated with seasonal influenza infection

Risks associated with inactivated seasonal influenza vaccination*

Common symptoms

  • Fever, sore throat, runny nose, dry cough, fatigue, headache, and muscle ache
  • Croup and bronchiolitis common in children

Common adverse event (<1/100)

  • Soreness/pain, redness and/or swelling around the injection site
  • Short-term fever (1–2 days), may be high (>39.0 C°) in children
  • Short-term fatigue (1–2 days)
  • Muscle ache (1–2 days)

Possible complications

  • Bacterial pneumonia
  • Ear infection
  • Sinus infection
  • Myocarditis
  • Pericarditis
  • Worsening of chronic medical condition present before influenza illness (e.g. congestive heart failure)
  • Precipitation of severe cardiovascular or cerebrovascular event

Rare adverse event (<1/1000)

  • Urticaria
  • Febrile convulsions in children

Rare complications

  • Septicaemia
  • Encephalopathy
  • Guillain-Barré syndrome**
  • Death

Very rare adverse event (<1/10.000)

  • Anaphylaxis
  • Paresthesia

*Reported risks refer to inactivated influenza vaccines commonly used in organised immunisation programmes in the European Union. For details see Summary of Product Characteristics for each vaccine available on national regulatory agency websites.

**Julia Stowe, Nick Andrews, Lesley Wise, Elizabeth Miller Investigation of the Temporal Association of Guillain-Barré Syndrome With Influenza Vaccine and Influenza-like Illness Using the United Kingdom General Practice Research Database, American Journal of Epidemiology, Volume 169, Issue 3, 1 February 2009, Pages 382–388 /C Vellozzi, D Burwen, A Dobardzic, R Ball, K Walton, P Haber Safety of trivalent inactivated influenza vaccines in adults: background for pandemic influenza vaccine safety monitoring, Vaccine, 27 (2009), pp. 2114-2120

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