Influenza, also known as flu, is a viral respiratory infection that can cause mild to severe symptoms. In some cases, flu can lead to life threatening complications and may be fatal.
According to the Centers for Disease Control and Prevention (CDC), the flu had a link to 34,200 deaths in the United States during the 2018–2019 influenza season.
Here we look at how flu can become life threatening, which people have a higher risk of complications, and what preventive steps a person can take against the flu.
Flu is not always the primary cause of death in cases of fatality. However, it can cause severe inflammation of the lungs that can cause acute respiratory failure and death.
Many cases of flu-related deaths are due to fatal complications.
If people have a compromised immune system, the body may find it harder to fight off infection. Certain people are at higher risk of flu complications, such as older adults, children, and pregnant women.
Likewise, flu can be dangerous for people with a good immune system. In some cases, the immune system has an overly extreme reaction to an infection. This reaction can harm organs and be fatal.
Flu can also cause pneumonia. Pneumonia is a severe inflammation of the lungs that causes the air sacs to fill with fluid. This reduces the amount of oxygen in the bloodstream. If cells in the body do not receive enough oxygen, it can lead to death.
Flu can trigger extreme inflammatory responses in the body. Serious complications include inflammation that can affect the:
- muscle tissues
In some cases, inflammation can cause organ failure.
If people get a secondary bacterial infection while experiencing flu, it can trigger sepsis. Sepsis is the body’s extreme reaction to infection and can be fatal.
If the body is slow to fight off the flu virus, people may have long-lasting illness. This continuation can make some individuals more susceptible to other infections.
It is difficult to know the exact number of deaths from flu each year, as reports may not contain every case.
States in the U.S. do not need to report a case of flu or flu-related death to the CDC for anyone over 18 years of age.
Also, doctors may not record flu as the cause of death when people die from flu-related complications. Many flu-related deaths are due to complications, such as worsening of an existing condition or a secondary infection.
This limation means data for flu-related deaths are often estimates. According to CDC data, from October 1, 2019, to April 4, 2020, in the U.S., there has been an estimated:
- 39 million–56 million cases of flu illnesses
- 18 million–26 million flu medical visits
- 410,000–740,000 hospitalizations due to flu
- 24,000–62,000 flu deaths
Flu-related deaths can also fluctuate from year to year. This can be due to a range of factors, such as different strains of the virus, variations in the number of people getting vaccinations, and when the flu season occurs.
The CDCestimate there were 12,000 flu-related deaths during 2011–2012 and 79,000 flu-related deaths during 2017–2018. Overall, they estimate there have been 12,000–61,000 flu-related deaths each year since 2010.
According to the European Centre for Disease Prevention and Control (ECDC), some 15,000–70,000 European citizens die every year of causes doctors associate with influenza.
Research estimates that 291,000–646,000 people die from flu-related respiratory illnesses worldwide each year.
The World Health Organization (WHO) suggests a similar range, estimating annual deaths due to seasonal influenza to be 290,000–650,000.
Severe and life threatening symptoms of flu and flu-related complications in adults can include:
- difficulty breathing
- pressure or pain in chest or abdomen
- dizziness and confusion
- worsening fever or cough
- worsening chronic health conditions
- lack of urination
- severe muscle pain
- weakness or loss of balance
If people experience any of these symptoms, they should seek immediate medical care.
In addition to the above symptoms, children may have:
- fever above 104°F
- bluish lips or face
- lack of alertness of interaction when awake
- fever in children under the age of 12 weeks
- no tears when crying or no urine for 8 hours due to dehydration
Risk factors for flu-related deaths include:
- adults aged 65 years or older
- children under 5 years of age, especially those under 2 years
- pregnant women and women up to 2 weeks after pregnancy
- chronic lung disease, such as asthma and chronic obstructive pulmonary disease (COPD)
- heart disease
- chronic kidney or liver disease
- children or adolescents taking long-term aspirin treatment
- conditions that compromise the immune system, such as HIV and AIDS
- treatments that compromise the immune system, such as chemotherapy or steroids
- morbid obesity
- neurological conditions
If people have symptoms of the flu, they will need to stay home to aid recovery and prevent passing the virus to others.
According to the WHO, vaccination is the most effective way to prevent flu. The flu vaccine is particularly important for people who have a higher risk of complications.
In particular, the WHO recommend annual flu vaccinations for:
- children aged 6 months to 5 years
- pregnant women
- adults 65 years and older
- people with chronic medical conditions
- healthcare workers
If people are less at risk of flu complications, getting the vaccine can help to prevent passing the virus on to people who are more vulnerable to infection. The severity of symptoms can also be unpredictable, so it is better to take extra precautions.
Regular hand washing is an important step in preventing the spread of germs. People should use soap and water, or if these are not available, an alcohol-based hand sanitizer.
When coughing or sneezing, this should be contained with a tissue to stop the spread of germs. People should then dispose of the tissue and clean their hands.
Avoiding close contact with anyone who is sick can help to reduce the spread of the virus.
People should be aware of emergency warning signs of flu, such as shortness of breath. If people experience severe symptoms or their symptoms become progressively worse, they should see a doctor.
Most people who get the flu will likely make a full recovery and may get better within 2 weeks or even a few days.
In some cases, flu can be life threatening and may cause death. Certain populations of people are more at risk of severe flu complications.
People can take precautions to help prevent getting flu. The flu vaccine is important for everyone over the age of 6 months to help protect themselves and others.
If people have severe or worsening flu symptoms or unusual symptoms, such as shortness of breath, they should see their doctor straight away. The sooner someone seeks medical support, the more effective treatment can be.