Groups at High Risk for Dangerous Flu Complications

While the flu is something that may simply lead to an unpleasant stretch for some people, certain groups are at higher risk for complications from the flu than others. Influenza infection can lead to pneumonia, bronchitis, hospitalization, and even death in high-risk individuals, such as children, older adults, those with chronic conditions, and others.

Understanding more about who is more likely to develop flu complications will not only help you better understand your and your family's personal risk but why it's so important to take measures to protect others who are most vulnerable as well.

Babies and Children

Children younger than 5 years—especially those under age 2—are at greatest risk for serious flu complications. Kids this age have immune systems that are still developing, and they are at risk of dehydration from fever (as is often seen with the flu).

Those younger than 6 months are also at great risk because they are too young to be vaccinated. As such, all people who come in contact with little ones should vaccinate themselves.

The flu vaccine is recommended for everyone 6 months and older (with rare exceptions). When the flu vaccine is in short supply, children ages 6 months to 4 years, and their caregivers and household contacts, are among the priority groups the Centers for Disease Control and Prevention (CDC) recommends for immunization.

The CDC reports alarming numbers of serious flu complications in children.

Since 2010, flu-related hospitalizations among children younger than 5 years have ranged from 6,000 to 27,000 a year.

The flu vaccine can significantly reduce the risk. A 2014 study showed that fully vaccinated children were 75% less likely to be hospitalized in the pediatric intensive care unit (ICU) than unvaccinated children.

The flu vaccine can reduce the risk of a child dying from influenza. A study of the 358 children who died of influenza from 2010 to 2014 found that the flu vaccine was 65% effective in preventing pediatric deaths, as well as 41% effective in preventing deaths in children who had high-risk medical conditions.

Pregnant and Postpartum Women

Those who are pregnant or have given birth in the past two weeks are more at risk of flu complications and hospitalization due to the virus than women who are not pregnant. This is because pregnancy changes the immune system, heart, and lungs. As well, fever can cause negative outcomes for a developing fetus.

The CDC recommends flu vaccination (via shot, not the live nasal vaccine) during pregnancy to protect both women and their babies during the first few months of life.

A study in 2018 analyzed the effectiveness of the flu vaccine in pregnancy. It found that the vaccine reduced the risk of hospitalization for flu during pregnancy by 40%.

Adults Over Age 65

The CDC estimates that between 70% and 85% of deaths from seasonal flu and between 50% and 70% of flu-related hospitalizations are in those aged 65 and over. Pneumococcal pneumonia is a flu complication that is of particular concern for this age group and can lead to death.

As the body ages, its ability to produce an immune response wanes, which can mean that the usual flu shot is not as effective in the older population. To improve the effectiveness of the flu shot in this age group, three specific flu vaccines are recommended for people 65 years and older:

  • Fluzone High-Dose Quadrivalent
  • Fluad Quadrivalent
  • Flublok Quadrivalent

Those With Chronic Health Conditions

For those of any age with chronic health problems, the flu can lead to the worsening of those conditions or the development of complications.

You are at increased risk when you have the following:

  • A weakened immune system: For example, due to cancer, HIV/AIDS, or chronic steroid medication use
  • Lung disease (e.g., asthma, COPD), in large part due to sensitive airways
  • Diabetes: The condition makes it harder for the body to fight infections such as pneumonia, bronchitis, or sinus infections. The CDC notes that about 30% of adult flu hospitalizations are people who have diabetes.
  • Heart disease
  • Extreme obesity
  • Neurological or neurodevelopmental conditions: For example, cerebral palsy, seizure disorders, intellectual disabilities, spinal cord injury
  • Liver disorders
  • Kidney disorders

American Indians, Alaska Natives, and people who live in nursing homes and other long-term care facilities are also at greater risk.

Complications of Influenza

Complications of the flu can be caused by the flu virus itself and your body's inflammatory response to it, or they can occur because your body is weakened by the flu and you develop a secondary infection.

Among the potential complications of the flu noted by the CDC:

  • Sinus infections and ear infections
  • Pneumonia: Due to the flu virus itself or other viruses or bacteria you are exposed to when you are weakened by the flu. Pneumonia can be deadly, especially for those who are in the risk groups for influenza complications.
  • Heart (myocarditis), brain (encephalitis), and muscle inflammation
  • Worsening of chronic heart disease
  • Multi-organ failure, including kidney failure and respiratory failure
  • Sepsis, an infection in the bloodstream
  • Asthma attacks/worsening symptoms in those who have asthma

Treatment for High-Risk Patients

If you contract the flu and are in a high-risk group, your healthcare provider will likely prescribe treatment with antiviral medications. Not only can these drugs lessen symptoms and reduce the time you're sick by one or two days, they can also mean the difference between mild illness and serious complications that warrant a hospital stay.

To be the most effective, you should start antiviral drugs within two days of getting sick. But even if there is a delay, these can still be beneficial for high-risk individuals. Antiviral medications are usually given for five days.

If you or someone you are caring for is in a high-risk group for flu complications, contact your healthcare provider as soon as symptoms of flu are noted (e.g., abrupt onset of fever, body aches, cough, or headache).

In addition to antiviral medications, you can treat symptoms of the flu to help reduce the risk of complications. Fevers can be reduced with age-appropriate fever-reducing medications such as Tylenol (acetaminophen). Children and teens under age 18 should not be given aspirin or any salicylate-containing medications as those can lead to the serious complication of Reye's syndrome.

Prevent dehydration by consuming plenty of clear, non-alcoholic fluids. Stay home and get rest until your fever has been gone for at least 24 hours without using a fever-reducing medication.

How Long is the Flu Contagious
 Verywell / Joshua Seong

If you develop a flu complication, you will need further treatment. For bacterial infections, antibiotics may be prescribed. These do not battle the flu itself, as it is a virus, but can work against secondary bacterial infections. These include bacterial pneumonia, sinus infections, ear infections, and sepsis.

With pneumonia and other complications affecting breathing, you might require hospitalization, breathing assistance, and treatment with intravenous fluids and medications.

Protecting Yourself

The best way to avoid the flu is to get a flu shot every year. Everyone in these high-risk groups, with very rare exception, should be vaccinated with a flu shot. The nasal spray flu vaccine is not recommended.

If your healthcare provider recommends against you getting the flu shot for some reason (e.g., an allergy), do your best to ensure those around you are vaccinated. This is especially true for any people who live with you, as well as close contacts you may have at work.

If you are over age 65, have a condition that compromises your immune system (such as cancer), or a lung disease such as asthma, be sure that you have appropriate pneumococcal immunizations. This can help prevent pneumonia if you get the flu.

Lastly, if you are exposed to the flu and are in a high-risk group, talk to your healthcare provider about starting antiviral medications. This can help prevent catching the flu or reduce the risk of complications should you become infected.

A Word From Verywell

The flu can be very serious for anyone, not just everyone included in the above list. It's more than just a bad cold—the flu claims the lives of thousands of people every year, even those who were previously healthy. Do what you can to avoid this serious illness.

13 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Kristina Duda, RN
Kristina Duda, BSN, RN, CPN, has been working in healthcare since 2002. She specializes in pediatrics and disease and infection prevention.