Risk factors
By Mayo Clinic staffFactors 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.
References
- Seasonal influenza — Questions & answers. Centers for Disease Control and Prevention. http://www.cdc.gov/flu/about/qa/disease.htm. Accessed Nov. 21, 2012.
- Key facts about influenza (flu) & flu vaccine. Centers for Disease Control and Prevention. http://www.cdc.gov/flu/keyfacts.htm. Accessed Nov. 21, 2012.
- Dolin R. Clinical manifestations of seasonal influenza in adults. http://www.uptodate.com/index. Accessed Nov. 21, 2012.
- What you should know about flu antiviral drugs. Centers for Disease Control and Prevention. http://www.cdc.gov/flu/antivirals/whatyoushould.htm. Nov. 21, 2012.
- Dolin R. Epidemiology of influenza. http://www.uptodate.com/index. Accessed Nov. 21, 2012.
- Longo DL, et al. Harrison's Online. 18th ed. New York, N.Y.: The McGraw-Hill Companies; 2012. http://www.accessmedicine.com/resourceTOC.aspx?resourceID=4. Accessed Nov. 21, 2012.
- Influenza antiviral medications: Summary for clinicians. Centers for Disease Control and Prevention. http://www.cdc.gov/flu/professionals/antivirals/summary-clinicians.htm. Accessed Nov. 21, 2012.
- Zachary KC. Treatment of seasonal influenza in adults. http://www.uptodate.com/index. Accessed Nov. 21, 2012.
- What you should know for the 2012-2013 influenza season. Centers for Disease Control and Prevention. http://www.cdc.gov/flu/about/season/flu-season-2012-2013.htm. Accessed Nov. 21, 2012.
- Preventing the flu: Good health habits can help stop germs. Centers for Disease Control and Prevention. http://www.cdc.gov/flu/protect/habits.htm. Accessed Nov. 21, 2012.
- Steckelberg JM (expert opinion). Mayo Clinic, Rochester, Minn. Nov. 30, 2012.
- Jefferson T, et al. Neuraminidase inhibitors for preventing and treating influenza in healthy adults and children. Cochrane Database of Systematic Reviews. http://www.thecochranelibrary.com/view/0/index.html. Accessed Nov. 24, 2012.


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