One reason some people give for not getting a flu shot is that they aren’t worried about getting sick. Unfortunately, the flu is much more serious than many people think. According to preliminary CDC estimates, last year’s flu season brought about 400,000 hospitalizations and roughly 22,000 deaths in the United States alone.

This is due to potentially deadly complications that can come with the flu. Anyone can experience them, but some are much more vulnerable than others. During flu season, these susceptible people rely on those around them to help protect them from the flu.


Possible complications

“Flu complications” often conjures the idea of high fevers or dehydration. While these are risks, there are others that are much deadlier and harder to treat.

“Bacterial pneumonia can happen with the flu,” said Anjali Mahoney, MD, a family medicine doctor at Keck Medicine of USC. “You can also get inflammatory reactions that can affect the heart (myocarditis), the brain (stroke, encephalitis and seizure) and sometimes even multiorgan failure. You can also get an extreme inflammatory reaction like the life-threatening cytokine storms you have heard about with COVID-19 that can cause sepsis.”


Age as a factor

Because their immune systems are still in the early stages of development, babies under 2 are particularly vulnerable to serious complications from the flu. For the same reason, babies 6 months and under are too young to withstand a flu vaccination. This means they have to rely on the older people around them to keep themselves immunized in order to protect them.

As people get older, their immune systems start to weaken, so anyone over 65 is susceptible to complications as well. Since the types of vaccines recommended for older patients are stronger, older patients sometimes find the side effects more difficult to tolerate.


Heart conditions and asthma

Studies have indicated a particular relationship between heart disease and the flu, indicating that getting influenza can take a serious toll on the heart, especially if someone is already living with a heart condition. When those with asthma catch the flu, they can face a worsening of their asthma symptoms and an increased risk for pneumonia.


Cancer patients

Cancer patients need to coordinate with their care team to work out the best time and type of flu shot for them as it relates to their treatment. Because cancer weakens the immune system so significantly, patients rely on those around them to minimize their exposure to influenza as much as possible — whether the patients themselves have been vaccinated or not. It’s therefore strongly recommended that anyone who knows a cancer patient get vaccinated against the flu.


Those who rely on immunosuppressants

People on immunosuppressants most often take them due to an organ transplant or to treat an autoimmune disease. While it may be clear if someone has had a recent transplant, people may not know if someone around them has an autoimmune disease such as lupus, Crohn’s disease, multiple sclerosis or sarcoidosis.

Because these conditions are often sensitive and personal, patients are not often likely to openly discuss this aspect of their health. That said, it is estimated that roughly 24 million people live with an autoimmune disease in the United States alone, so it’s very possible for any one person to know someone with one of these conditions.

— Kate Faye