Flu Season 2020: Is it fatal? Kids younger than 5 and people 65 and older at high risk of complications
Flu is a viral infection that attacks a person’s respiratory system: nose, throat, and lungs. For many, the common flu resolves on its own, but sometimes, influenza and its complications can be deadly. The US Centers for Disease Control and Prevention (CDC) estimates that about 22,000 Americans died from the flu during the previous 2019-2020 flu season. Besides, flu resulted in 38 million illnesses and 400,000 hospitalizations during 2019-2020. According to the agency, the flu has caused 12,000 to 61,000 deaths annually in the US since 2010.
Respiratory complications, such as pneumonia, are the most common reason for people to be hospitalized from flu. However, a recent JAMA Network Open study sheds new light on the number and impact of people hospitalized from flu for non-respiratory complications. Examining medical records of over 76,000 adult flu patients hospitalized from 2010 through 2018, the authors found that most had an acute respiratory complication as expected, but, nearly half also had a non-respiratory complication and 5% of patients only experienced a non-respiratory complication from their flu infection. The most common acute non-respiratory complications reported were sepsis (23.3%), acute kidney injury (20.2%) and acute cardiovascular events (12.1%).
The CDC says that about 1 in 10 Americans will become sick with flu in any given season, and some people are at increased risk of developing influenza-related complications. So which groups are at high risk?
Adults 65 years and older
People who are 65 years and older are at greater risk of developing serious complications from the flu compared to young, healthy adults. This risk is due in part to changes in immune defenses with increasing age.
While flu seasons vary in severity, during most seasons, people 65 years and older bear the greatest burden of severe flu disease. In recent years, for example, the CDC estimates that between 70% and 85% of seasonal flu-related deaths have occurred in people in this age group. About 50% and 70% of seasonal flu-related hospitalizations have occurred among people 65 years and above.
Flu is more dangerous than the common cold for children. Each year, the flu places a large burden on the health and well-being of children and their families. The CDC estimates that since 2010, flu-related hospitalizations among American children younger than 5 years old have ranged from 7,000 to 26,000. Some children also die from the flu each year. Since 2004-2005, flu-related deaths in children reported to CDC during regular flu seasons have ranged from 37 to 188. The highest hospitalization and death rates are among infants younger than 6 months old.
Children younger than 5 years old – especially those younger than 2 – are at increased risk of developing serious flu-related complications and in some cases, complications can lead to death. Complications from flu among children can include pneumonia, dehydration and worsening of long-term medical problems like heart disease or asthma. Other complications are brain dysfunction such as encephalopathy, sinus problems and ear infections.
Children with neurologic conditions
Children of any age with neurologic conditions are more likely than other children to become very sick if they get the flu. Some children with neurologic conditions may have trouble with muscle function, lung function or difficulty coughing, swallowing or clearing fluids from their airways. These are problems that can make flu symptoms worse.
People with chronic medical conditions
Heart disease: People with heart disease and those who have had a stroke are at higher risk for developing serious complications from the flu. Heart disease can include heart failure, congenital heart defects, hypertensive heart disease, heart valve disorders, arrhythmias including atrial fibrillation, and pulmonary heart disease. Studies suggest that flu illness is linked with an increase in heart attacks and stroke. A 2018 study found that the risk of heart attack was 6 times higher within a week of confirmed flu infection. These findings were most pronounced for older adults and those experiencing their first heart attack. A 2020 study that examined over 80,000 American adults hospitalized with flu over eight flu seasons (2010-11 through 2017-18) found that sudden, serious heart complications were common and occurred in approximately 12% of patients.
Asthma: A lung disease that is caused by chronic inflammation of the airways, people who have this condition are at high risk of developing serious flu complications. The risk stays even if their asthma is mild or their symptoms are well-controlled by medication. Flu infections can trigger asthma attacks and a worsening of asthma symptoms. It can also lead to pneumonia and other acute respiratory diseases. “Adults and children with asthma are more likely to develop pneumonia after getting sick with flu than people who do not have asthma. Asthma is the most common medical condition among children hospitalized with flu and one of the more common medical conditions among hospitalized adults,” says the CDC.
Diabetes: People with diabetes (type 1, type 2, or gestational), even when well-managed, are a high-risk group. They can suffer flu-related complications, which can result in hospitalization and sometimes even death. Pneumonia, bronchitis, sinus infections and ear infections are examples of flu-related complications. About 30% of flu hospitalizations reported to CDC in recent seasons have been in adults with diabetes. Flu also can make diabetes worse, diabetes can make the immune system less able to fight infections. Flu may raise sugar levels, but sometimes people do not feel like eating when they are sick and a reduced appetite can cause blood sugar levels to fall.
HIV/AIDS: People with HIV -- especially those who have a very low CD4 cell count (very suppressed immune system) or who are not taking medicine to treat HIV (antiretroviral therapy, or ART) -- can suffer from serious flu-related complications. Research suggests that flu symptoms might be prolonged and the risk of flu-related complications and prolonged flu virus shedding is higher for certain people living with HIV.
Chronic kidney disease (CKD): The risk of developing serious flu complications, which can result in hospitalization and even death, is high among people with this health condition. This is because CKD weakens immune response, which can make the immune system less able to fight infections. People with CKD at any stage, those who have had a kidney transplant and those undergoing dialysis treatment are all at an increased risk of severe illness from the flu.
The JAMA Network Open analysis also highlights the increased risk of influenza-associated complications for people with underlying medical conditions. Among patients with at least one acute respiratory complication, 43% had an underlying respiratory medical condition, such as asthma or chronic obstructive pulmonary disease (COPD). Among patients with an acute non-respiratory complication, there was a significantly higher frequency of underlying medical conditions, including metabolic (52%), cardiovascular (51%), renal (33%), neurological (30%), immunosuppressive (19%), hepatic (7%), and hematologic (6%). “This new evidence emphasizes the increased risk of influenza complications for people with underlying medical conditions and provides a reminder as to why influenza vaccination and the prompt use of antiviral medication is so important for people with underlying health conditions,” writes the research team.
Flu is more likely to cause severe illness in pregnant women as compared to women of reproductive age who are not pregnant. The reason: changes in the immune system, heart, and lungs during pregnancy make pregnant women (and women up to two weeks postpartum) more prone to severe illness from flu, including illness resulting in hospitalization. According to health experts, flu may also be harmful to a pregnant woman’s developing baby. A common flu symptom is a fever, which may be associated with neural tube defects and other adverse outcomes for a developing baby.
Other people at high risk from the flu
People who live in nursing homes and other long-term care facilities, people who are obese with a body mass index of 40 or higher, those with liver disorders, and people with a weakened immune system due to disease (such as those with some cancers like leukemia) or medications (such as those receiving chemotherapy or radiation treatment for cancer), are high-risk groups. People from certain racial and ethnic minority groups are at increased risk for hospitalization with flu, including non-Hispanic Black persons, Hispanic or Latino persons, and American Indian or Alaska Native persons.