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Those who belong to the following groups are at greater risk for contracting the flu virus. They are also at greater risk for developing secondary infections or other complications.
Children under 5 years old are more likely than most adults to have health complications from the flu virus. This is because their immune system is not fully developed.
According to the Centers for Disease Control and Prevention (CDC), children under 2 and those who have weakened immune systems are at an even greater risk for flu-related complications. Children with chronic health problems (such as diabetes or asthma) are also at risk for the development of complications from the flu.
These complications can include:
Older adults are also at greater risk for serious complications from the flu. This is because the immune system typically weakens with age.
Flu infection can also worsen long-term health problems such as heart disease, lung disease, and asthma.
Each year in the United States, people 65 years or older account for more than 60 percent of those hospitalized for flu-related complications. They account for 90 percent of flu-related deaths, according to the CDC.
The U.S. Food and Drug Administration (FDA) recently approved a special high-dose vaccine for people 65 and over called Fluzone High-Dose. This vaccine may help to improve the specific anti-influenza immune response of vaccine recipients in this age group. Talk to your doctor for more details about this newer vaccine.
Pregnancy increases the chance of serious flu-related complications to both mother and unborn child.
Fever is a common symptom of the flu. It should be treated immediately because of the harmful effects it can have on the unborn child.
According to the CDC, the flu shot is the best protection against flu-related complications for both mother and child (up to 6 months old). However, the nasal spray form of the vaccine is unsafe for pregnant women because unlike the injectable vaccines, a small risk for actually developing flu exists with the nasal spray form.
HIV/AIDS patients and others with weakened immune systems are at greater danger of complications from a flu infection. Cancer treatments and regular use of corticosteroid drugs can also weaken the immune system.
A weakened immune system is less able to fight off flu infection.
Children and teens who are receiving long-term treatment with aspirin (or other salicylate containing medication) are at elevated risk for developing Reye’s syndrome if they develop an acute viral illness with fever, particularly the flu.
Reye’s syndrome is a rare disorder in which there is sudden brain and liver damage of uncertain cause. However, it’s known to occur about a week after a viral infection when salicylates have been given. Young people on chronic aspirin or salicylate therapy must receive flu vaccination in order to prevent this potential complication.
People with the following conditions are at greater risk for infections:
The increased risk is due to weakened immune systems, whether caused by the condition or by the treatments.
People who live or work in heavily populated places with close interpersonal contact are also at greater risk for contracting the flu virus. Examples of these kinds of places include:
Frequent handwashing and the use of antibacterial products may help to reduce this risk.
People who fall into any of the above categories should receive first priority with regard to yearly flu shots.
According to the CDC, the nasal spray vaccine is not recommended for people with medical conditions, children under the age of 2, or women who are pregnant.
High-risk individuals should also see a doctor immediately if they show any symptoms of the flu. The first 48 hours after symptoms appear provides the best window for effective treatment.
In some cases, doctors may want to prescribe antiviral medications.
Healthy individuals can sometimes also have flu-related complications, depending on the flu strain.
According to an article published in PLOS One, during the H1N1 flu pandemic of 2009, better known as "swine flu," flu complications resulted in the deaths of adults in their 20s and 30s. People over 60 had the lowest rate of infection.
This was a rare instance. Flu viruses almost never significantly harm healthy people in this age group.
This suggests that this was a new, atypical, and more severe strain of virus that these younger individuals’ bodies had never been exposed to.
There is also some belief that the older individuals were better protected from this particular strain. This is because the 2009 H1N1 virus was similar to a flu virus from the 1950s. These older individuals’ bodies may have retained immunity that those younger individuals did not have.
For both healthy and at-risk individuals, the best defense against the flu is a yearly flu shot. The CDC recommends that everyone 6 months of age and older receive the vaccine.
Written by: the Healthline Editorial Team
Medically reviewed on: Oct 20, 2014: Brenda B. Spriggs, MD, MPH, MBA
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