Can a flu shot be administered to an individual who is acutely ill?

Can You Give a Flu Shot When Acutely Ill?

Minor illnesses with or without fever do not contraindicate influenza vaccination, but persons with moderate to severe acute febrile illness should defer vaccination until their symptoms have resolved. 1

Key Decision Framework

The decision to vaccinate depends on illness severity, not simply the presence of symptoms:

Minor Illness (Vaccinate Now)

• Minor upper respiratory infections (runny nose, mild sore throat) with or without fever are NOT contraindications 1, 2
• Allergic rhinitis does not preclude vaccination 1, 2
• Mild diarrhea does not contraindicate vaccination 1
• Low-grade fever alone without moderate-to-severe systemic symptoms is acceptable 1

Moderate to Severe Illness (Defer Vaccination)

• High fever with active infection requiring hospitalization should prompt deferral 1
• Moderate to severe febrile illness of any cause warrants postponement until resolution 1
• The rationale is to avoid confusing post-vaccination symptoms with progression of the underlying illness, not because the vaccine is unsafe 1

Special Considerations by Vaccine Type

Injectable Inactivated Vaccines (IIV)

• Can be safely administered during rhinitis regardless of severity 2
• No special precautions needed beyond standard vaccination practices 2
• Minor respiratory symptoms do not affect vaccine delivery or efficacy 1

Live Attenuated Intranasal Vaccine (LAIV)

• Can be given with mild rhinitis 1, 2
• Should be deferred if significant nasal congestion would impede vaccine delivery to the nasopharyngeal mucosa 1, 2
• Alternative: administer injectable vaccine instead if congestion is problematic 1

COVID-19 Context

For patients with confirmed COVID-19:

• Defer vaccination if moderate or severe illness until recovery 1
• Mild or asymptomatic COVID-19: further deferral may be considered to avoid confusing COVID-19 symptoms with post-vaccination reactions 1
• Do not bring patients in quarantine or isolation to vaccination settings if this could expose others 1

Common Pitfalls to Avoid

• Don't over-defer: Minor symptoms like mild cold, low-grade fever, or allergic rhinitis are NOT reasons to postpone vaccination 1, 2
• Don't confuse precautions with contraindications: Moderate-to-severe illness is a precaution (temporary deferral), not an absolute contraindication 1
• Clinical judgment matters: The decision should be based on whether the patient appears systemically ill, not just the presence of any symptom 1
• For LAIV specifically: Don't forget to assess nasal patency—significant congestion requires either deferral or switching to injectable vaccine 1

Bottom Line Algorithm

1. Assess illness severity (not just presence of symptoms)
2. Minor illness → Vaccinate today with any appropriate vaccine type
3. Moderate-to-severe illness → Defer until resolution
4. If using LAIV with nasal congestion → Either defer or switch to injectable vaccine
5. When in doubt with borderline cases → Vaccinate, as the benefits of timely protection typically outweigh theoretical concerns about symptom confusion 1