Factors that may increase your risk of developing influenza or its complications include:

  • Age. Seasonal influenza tends to target young children and people over 65. The pandemic H1N1 virus that surfaced in 2009, however, appeared to be most common in teenagers and young adults.
  • Occupation. Health care workers and child care personnel are more likely to have close contact with people infected with influenza.
  • Living conditions. People who live in facilities along with many other residents, such as nursing homes or military barracks, are more likely to develop influenza.
  • Weakened immune system. Cancer treatments, anti-rejection drugs, corticosteroids and HIV/AIDS can weaken your immune system. This can make it easier for you to catch influenza and may also increase your risk of developing complications.
  • Chronic illnesses. Chronic conditions, such as asthma, diabetes or heart problems, may increase your risk of influenza complications.
  • Pregnancy. Pregnant women are more likely to develop influenza complications, particularly in the second and third trimesters.
Feb. 21, 2013