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Experts are learning who is at highest risk of sever COVID-19 symptoms. Getty Images
  • Tens of millions of Americans have a chronic health condition that increases their risk of severe illness from COVID-19.
  • While older age and underlying medical conditions, including diabetes and obesity, increase a person’s risk of severe COVID-19, some healthy people have also been severely affected by the new coronavirus.
  • SARS-CoV-2 is not just a respiratory virus that affects the lungs. It can also affect the stomach, intestines, heart, blood vessels, liver, kidneys, and the immune system.

In the United States, 6 out of 10 adults have a chronic disease that increases their risk of severe COVID-19. Also, 4 out of 10 people have two or more of these chronic conditions.

That means that millions of Americans have a higher risk of becoming seriously ill or dying from COVID-19.

“If you have underlying conditions, including obesity and other [chronic] diseases, you are at much higher risk of hospitalization, serious complications, and death [from COVID-19],” said Barry M. Popkin, PhD, a professor of nutrition in the UNC Gillings School of Global Public Health in Chapel Hill, North Carolina.

This makes it even more important for people at risk to take steps to protect themselves from SARS-CoV-2, the coronavirus that causes COVID-19.

The Centers for Disease Control and Prevention (CDC) lists several medical conditions that increase a person’s risk of developing severe COVID-19.

Many of these are very common among Americans:

  • Cancer. An estimated 1.8 million Americans will be diagnosed with cancer this year, with breast and lung cancer the most common types. In 2017, an estimated 15.7 million Americans were living with cancer.
  • Chronic kidney disease. Around 37 million U.S. adults have chronic kidney disease, but 9 in 10 adults don’t know they have it.
  • Chronic obstructive pulmonary disease (COPD). About 16 million Americans have emphysema, chronic bronchitis, or another COPD lung condition. These are more common among adults with lower income, public insurance, and a history of smoking.
  • Heart disease. An estimated 30.3 million U.S. adults have diagnosed heart disease. Millions more may have an undiagnosed heart condition.
  • Obesity. More than 42 percent of American adults — around 108 million — have obesity. Obesity occurs in 40 percent of young adults ages 20–39. Popkin said the high obesity rate in the United States “may be one explanatory factor behind our high COVID-linked mortality.” He recently co-authored a paper looking at the link between obesity and COVID-19.
  • Sickle cell disease. This genetic disease affects about 100,000 Americans, including 1 in 365 Black Americans.
  • Type 2 diabetes mellitus. More than 32 million Americans have type 2 diabetes, with over 7 million cases undiagnosed. In 2015, an additional 88 million American adults had prediabetes, the early stage of this condition.
  • Weakened immune system from organ transplant. Almost 40,000 organ transplants were performed in 2019, with more than 750,000 performed since 1988.

According to the CDC, other conditions and factors might also increase a person’s risk, but there isn’t enough data yet to know for certain. These include:

  • asthma
  • cerebrovascular disease, which affects the blood vessels and blood supply to the brain
  • cystic fibrosis
  • damaged or scarred lung tissues (pulmonary fibrosis)
  • hypertension, or high blood pressure
  • liver disease
  • neurologic conditions, such as dementia
  • pregnancy
  • smoking
  • thalassemia, a type of blood disorder
  • type 1 diabetes mellitus
  • a weakened immune system due to blood or bone marrow transplant, immune deficiencies, HIV, or use of corticosteroids or other immune weakening medications

There’s still a lot that scientists don’t know about COVID-19 and what causes it, including why some people get more severe illness.

While older age and underlying medical conditions increase a person’s risk of severe COVID-19, some healthy people have also been severely affected by the coronavirus.

Data from the CDC shows that 6 percent of the more than 180,000 deaths from COVID-19 had no other cause listed on the death certificate.

While some people had other conditions that contributed to their death, this doesn’t mean that they didn’t die from COVID-19.

“The point the CDC was trying to make was that a certain percentage of them had nothing else but just COVID,” said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, in an interview with “Good Morning America.”

“That does not mean that someone who has hypertension or diabetes who dies of COVID didn’t die of COVID-19. They did,” he added.

In addition, many of the other factors listed in the CDC’s report are conditions that are caused by SARS-CoV-2 — such as pneumonia, acute respiratory distress syndrome, heart failure, and kidney failure.

If COVID-19 led to pneumonia or acute respiratory distress syndrome, then it is COVID-19 that’s the primary cause of death.

The coronavirus isn’t just a respiratory virus that affects the lungs. It can also affect the stomach, intestines, heart, blood vessels, liver, kidneys, and immune system.

Part of the damage is caused by an overreactive response of the immune system to the virus — what’s known as a “cytokine storm.”

In addition to obesity, diabetes is another COVID-19 risk factor that’s of particular concern for millions of Americans, especially for those with undiagnosed — and unmanaged — high blood sugar.

Dr. Roma Gianchandani, a professor of internal medicine in the University of Michigan’s Michigan Medicine division of metabolism, endocrinology, and diabetes, said people with diabetes have a higher risk of severe illness with COVID-19, although it’s not clear yet how much diabetes alone contributes to that.

“Diabetes patients have increased severity of COVID-19,” she said. “Some of this is due to other conditions like heart disease that coexist [with diabetes], in addition to diabetes complications.”

There’s also an interplay between diabetes and COVID-19 that can worsen patient outcomes.

“Diabetes patients have a baseline level of inflammation which is worsened by infections,” said Gianchandani, which can be even worse in patients with poorly managed blood sugar levels.

People with diabetes often have high blood pressure, or heart or kidney disease, all of which increase a person’s risk of severe COVID-19.

Gianchandani said COVID-19 also causes inflammation, which can raise blood sugar levels in people with diabetes. If the inflammation is severe enough, it can even increase blood sugar in people without diabetes.

She and her colleagues are working on better ways to monitor and manage high blood sugar levels in COVID-19 patients. They published their preliminary results recently in the journal Diabetes.

Their tool is designed for use with diabetes patients in the hospital, but Gianchandani said the concept applies to others as well.

“Patients with diabetes who are at home and well should absolutely monitor and follow their blood glucose levels closely, work with their physician offices, and maintain a good diabetes management regimen,” she said.

“It is also important for them to follow all the COVID-19 prevention measures to avoid getting the disease,” she added.

These are good tips for anyone with an underlying health condition. On its website, the CDC lists actions that people with chronic conditions can take in order to reduce their risk of severe COVID-19.