Should an individual with influenza-like symptoms receive a vaccine?

From the Guidelines

You should not get a vaccine if you have moderate to severe flu-like symptoms, but mild illnesses without fever are not contraindications to vaccination. According to the most recent guidelines from 2024, all persons aged ≥6 months without contraindications should be vaccinated annually 1. However, the presence of fever or moderate to severe illness might reduce your body's ability to build an effective immune response to the vaccine. The 2016 study published in Pediatrics suggests that minor illnesses, with or without fever, are not contraindications to the use of influenza vaccines, particularly among children with mild upper respiratory infection symptoms or allergic rhinitis 1.

Key Considerations

• Mild illnesses without fever, such as a minor cold, are typically not reasons to postpone vaccination.
• Moderate to severe febrile illness, based on the judgment of the clinician, should be a contraindication to vaccination until resolution of the illness.
• If you're unsure about your symptoms, consult with your healthcare provider who can assess your specific situation and advise whether to proceed with vaccination or wait until you've recovered.
• Once your symptoms have resolved, you can safely receive your vaccine to gain protection against future infections.

Important Exceptions

• Infants younger than 6 months should not be vaccinated with IIV.
• A previous severe allergic reaction to influenza vaccine is a contraindication to future receipt of the vaccine.
• People who are not at high risk of severe influenza illness should be vaccinated, but those with a history of Guillain-Barré syndrome within 6 weeks of influenza vaccination generally should not be vaccinated, unless the benefits outweigh the risks.

From the Research

Influenza Vaccination and Flu-like Symptoms

• If you have flu-like symptoms, it is still recommended to get vaccinated against influenza, as the vaccine can help prevent severe complications and hospitalization 2, 3.
• The influenza vaccine is the primary preventive measure against influenza, and it is recommended for all people 6 months of age or older, including pregnant and postpartum women, unless the individual has a contraindication 2.
• Vaccination can reduce the number of deaths linked to influenza by about 80%, hospitalization and pneumonia by about 50%, and symptomatic influenza by about 30% in people over 65 years of age 4.

Antiviral Drugs and Influenza

• Antiviral drugs, such as oseltamivir, can be used as an adjunct to vaccination in some situations, particularly for unvaccinated individuals who are at high risk of infection and severe complications 4, 3.
• Oseltamivir has been shown to reduce the frequency of serologically confirmed episodes of influenza and can be effective in preventing lower respiratory tract complications in influenza cases 5.
• However, the use of antiviral drugs should be limited to situations where a major potential benefit exists, and they should not be used as an alternative to influenza vaccination 4, 5.

Effectiveness of Influenza Vaccination

• The effectiveness of influenza vaccination can vary by year, but it has been shown to offer significant protection against influenza-associated hospitalization in children, with an estimated vaccine effectiveness of 57.48% 6.
• Influenza vaccination has been shown to be more effective against certain types and strains of influenza, such as H1N1 and influenza B, and less effective against others, such as H3N2 6.
• Complete annual vaccination is recommended, as it can provide higher protection against influenza-related hospitalization compared to partial vaccination 6.