Influenza risk factors

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For more information about non-human (variant) influenza viruses that may be transmitted to humans, see Zoonotic influenza

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Alejandro Lemor, M.D. [2]

Overview

Risk factors for influenza include those that increase exposure to the virus such as healthcare settings, nursing homes, and daycare. Additionally, there are certain groups that are at risk for more severe disease and complications, particularly children younger than 2 years old, adults aged 65 or older, pregnant women, patients with comorbidities, asthmatic patients, and patients with a weakened immune system.

Risk Factors

• Healthcare workers are at a higher risk of developing influenza infection due to their exposure to patients in the daily bases.
• Persons at higher risk for severe influenza disease and complications include the following conditions shown in the table below.

High Risk for Developing Flu-Related Complications
Children aged younger than 2 years	Asthmatic patients
Adults aged 65 years and older	Blood disorders (such as sickle cell disease)
Kidney disorders	Pregnant women
Liver disorders	Metabolic disorders (such as inherited metabolic disorders and mitochondrial disorders)
Heart disease, such as: Congenital heart disease Congestive heart failure Coronary artery disease	Neurologic and neurodevelopment conditions (including disorders of the brain, spinal cord, peripheral nerve, and muscle such as cerebral palsy, epilepsy, stroke, intellectual disability [mental retardation], moderate to severe developmental delay, muscular dystrophy, or spinal cord injury)
Persons aged younger than 19 years who are receiving long-term aspirin therapy	Persons with immunosuppression, including that caused by medications, cancer or by HIV infection
American Indians/Alaska Natives	Residents of nursing homes and other chronic-care facilities.
Persons who are morbidly obese (BMI > 40)
Adapted from CDC