COVID-19 and Pre-Existing Conditions: Understanding Your Risk

9 Factors That Increase the Risk and Severity of Coronavirus Infection

pre-existing conditions and COVID-19

Verywell / Ellen Lindner

By the time the very first cases of the new coronavirus (COVID-19) were identified in the United States in January 2020, it was already clear that certain groups were at greater risk of serious illness, and possibly death, than others. In an effort to protect vulnerable populations, the Centers for Disease Control and Prevention (CDC) issued a list of those at greatest risk due to pre-existing health conditions.

At first, the guidance seemed to focus on many of the same groups who are at risk of severe illness from the flu—including the elderly and people with chronic lung disease—but, by the time a national emergency was declared on March 13, 2020, it became imminently clear that this was not the flu.

The list of vulnerable populations grew, but failed to include some groups we typically see on at-risk lists, like babies. This has led to some confusion about the nature of the virus and why it causes serious illness in some but not in others.

Because COVID-19 is such a new disease—and information about the virus is still evolving—the CDC has taken extraordinary steps to protect not only groups who have already been hard-hit by the pandemic but those who are presumed to be at risk based on experience with other coronavirus outbreaks, like the SARS outbreak of 2003 and the MERS outbreaks of 2012, 2015, and 2018.

It is important to understand that having one or more risk factors for COVID-19 does not mean that you’re destined to fall seriously ill. And having none doesn't mean that you are automatically "safe."

What the CDC guidance illustrates is that, until scientists know more about this novel coronavirus, people who are older or have pre-existing conditions need to take extra precautions to keep themselves safe during the pandemic.

Adults 65 and Over

According to the CDC, eight of every 10 deaths in the U.S. from COVID-19 have been in adults 65 and older. The risk only increases with age; the CDC estimates anywhere between 10% to 27% of adults 85 and older are likely to die if they are infected with COVID-19.

Among adults ages 65 to 84, between 31% and 59% will need hospitalization if they get COVID-19. Of those, between 4% to 11% will die. The picture among adults 85 and over is even more concerning, with as many as 70% requiring hospitalization and up to 27% in this age group dying.

There are several reasons for this, some of which are interrelated:

  • Loss of immune function: A person’s immune function invariably decreases with age, making them less able to fight common and uncommon infections.
  • Inflammation: Because the immune system of older adults is often impaired, it tends to over-respond with inflammation in an effort to curb the infection. High levels of inflammation can effectively "spill over" from the site of the infection (in this case, the lungs) and affect multiple organ systems.
  • Complications: Because older adults generally have multiple health concerns, a severe respiratory infection can end up complicating a pre-existing heart, kidney, or liver condition.
  • Decreased lung function: Because the lungs lose much of their elasticity with age, they are less able to sustain breathing without ventilation if a pneumonia-like infection develops.

Due to the underlying health risks, the CDC strongly advises that people 65 and over stay at home during the pandemic and maintain social distancing if out in public.

Chronic Lung Disease

COVID-19 is a respiratory virus that attaches to cells via proteins known as ACE2 receptors. ACE2 receptors occur in high density in the esophagus (windpipe) and nasal passages, where the virus can cause upper respiratory symptoms. But, in some people, the virus can move deeper into the lungs to the alveoli where ACE2 receptors also proliferate, causing severe and potentially life-threatening acute respiratory distress syndrome (ARDS).

It no surprise, therefore, that people with chronic lung diseases are considered to be at high risk for experiencing complications once infected with COVID-19. These include respiratory conditions like:

The risk can vary by the type of disease involved:

  • COPD and interstitial lung disease are characterized by progressive scarring (fibrosis) and the loss of lung elasticity. This can reduce a person's ability to breathe on their own should an infection occur.
  • Asthma does not cause scarring, but there is concern that the infection could trigger a severe and potentially life-threatening attack, particularly in people with poor asthma control.
  • Cystic fibrosis and bronchiectasis are associated with excess mucus production. If pneumonia were to develop as a result of COVID-19, the obstruction of airways can become life-threatening.

Despite these vulnerabilities, there remains debate on how at-risk people with chronic lung disease truly are.

According to an April 2020 study in Lancet Respiratory Medicine, people with COPD or asthma do not appear to be at greater risk of either getting COVID-19 or experiencing worse symptoms than other groups.

It is important, however, to put the Lancet Respiratory Medicine findings into context, and understand that the risk from a statistical standpoint is not the same as the risk from an individual standpoint.

People with advanced or poorly controlled lung disease, particularly those who smoke, are more likely than not to have compromised immune systems. It is in this group that an uncomplicated upper respiratory infection can suddenly move into the lungs and turn severe.

Immunocompromised People

Immunocompromised people are those whose immune systems are weak, making them less able to fight infection. The loss of immune strength not only increases the risk of infection but increases the likelihood of severe disease.

Immune suppression characteristically affects:

However, not all groups are affected equally. As with chronic lung diseases, there is conflicting evidence as to how vulnerable people with HIV actually are.

According to research presented Conference on Retroviruses and Opportunistic Infections in March 2020, investigators could find no association between the incidence and severity of COVID-19 in people with HIV, even those with significant immune suppression. The same was not seen in other at-risk groups.

According to research, organ transplant recipients (most especially kidney recipients) and people undergoing chemotherapy are far more likely to get COVID-19 and develop ARDS as a result of the infection.

It is believed that the widespread use of antiretroviral drugs in people with HIV may undercut the risk by restoring the immune function. If so, people not on antiretroviral therapy may be at as far greater risk of COVID-19.

Heart Disease

The respiratory and cardiovascular systems are inherently linked. Any oxygen delivered to the lungs is dispersed throughout the body by the heart. When a respiratory infection limits the amount of air that enters the lungs, the heart has to work harder to ensure that the diminished oxygen supply reaches vital tissues.

In people with pre-existing cardiovascular disease, the added stress on the heart not only increase the severity of high blood pressure but also the likelihood of a heart attack or stroke.

According to a March 2020 study in JAMA Cardiology involving 187 people hospitalized for COVID-19, nearly 28% experienced a coronary event, including heart attack, while in hospital. Those who did were nearly twice as likely to die compared to those with no heart event (13.3% versus 7.6%, respectively).

Moreover, people with pre-existing heart conditions were three times more likely to die as a result of COVID-19 than those with no pre-existing heart condition.


Type 1 and type 2 diabetes can both cause abnormal increases in blood sugar (hyperglycemia) if not properly controlled. The inability to control blood sugar is the main reason why certain people with diabetes are more likely to get COVID-19 and experience worse disease.

Acute hyperglycemia can lead to a condition called diabetic ketoacidosis, in which acids known as ketones impair the production of immune cells (including T-cell lymphocytes and neutrophils). This can increase a person's vulnerability to infection, particularly when faced with a new virus like COVID-19.

Ketoacidosis is rare, particularly in type 2 diabetes, so it doesn't necessarily explain why diabetics have been shown to be at a higher risk. However, many people with diabetes still have some overall level of immune suppression.

According to a March 2020 study published in JAMA involving 72,314 people with COVID-19 in Wuhan, China, diabetes was associated with no less than a three-fold increase in the risk of death compared to people without diabetes.

While other studies have not described such dramatic increases—showing instead that diabetes occurring with other risk factors, such as older age and hypertension, are associated with an increased risk—there is evidence that blood glucose control does, in fact, impact outcomes.

According to a March 2020 study in Metabolism, maintaining normal blood sugar in people with type 2 diabetes appears to decrease the risk of getting COVID-19 and developing severe illness.

Liver Disease

Getting COVID-19 may complicate pre-existing liver disease in some people, as evidenced by research in which liver enzymes, most especially aminotransferases, are raised in those infected. Raised aminotransferases are an indication of liver inflammation and the worsening of liver disease, including viral liver diseases like hepatitis C.

While it is unknown how much COVID-19 affects people with liver disease in general, most studies suggest that problem is limited to the severely ill.

Although some experts believe that COVID-19 causes direct liver injury, many of the drugs used to treat severe respiratory infections (including antibiotics, antivirals, and steroids) are known to damage the liver as well.

A March 2020 review of studies in the Lancet reported that people hospitalized for COVID-19 are twice as likely to have extreme elevations of aminotransferase and bilirubin levels. Even so, few people experienced any liver damage, and the increases in liver enzymes, while concerning, were usually short-lived.

Chronic Kidney Disease

Chronic kidney disease (CKD) appears to increase the risk of severe illness and death in people with COVID-19. The risk appears to rise in tandem with the severity of the disease, with people on dialysis at greatest risk (although harm has also occurred in those with stage 3 and 4 CKD).

People with advanced CKD typically have suppressed immune systems, but other factors can contribute to an increased risk of illness in people with COVID-19. Because the function of the lungs, heart, and kidneys are interrelated, any impairment of one organ will invariably impact the others. If a severe lung infection were to occur, any impairment of the kidney would almost invariably be amplified.

According to March 2020 study in Kidney International, the risk of death from COVID-19 is doubled if pre-existing kidney disease is involved. Most deaths occur when a systemic infection causes acute renal failure, typically in critically ill patients with advanced CKD.

Despite the concerns, research published in the American Journal of Nephrology concluded that acute renal failure is still a relatively uncommon occurrence with COVID-19 and that COVID-19 will not aggravate CKD in most people.


Obesity encompasses many of the health conditions associated with the increased risk and severity of COVID-19, including:

In addition, obesity is associated with impaired immunity, due in part to the persistent inflammation that "blunts" the activation of the immune system. This is evidenced by high rates of failure in response to certain vaccines, including the H1N1 ("swine flu") vaccine and the hepatitis B vaccine.

Other researchers have suggested that higher rates of obesity in Italy may account for the increased COVID-19 mortality rate in that country compared to China.

Neurological Disorders

Although not included in the CDC's list of risk factors, some scientists have noted that certain neurological disorders, like multiple sclerosis (MS), Parkinson's disease, or motor neuron diseases, may increase the severity of a COVID-19 infection by impairing swallowing (known as bulbar weakness), diminishing the cough reflex, or causing weakness of respiratory muscles.

At the same time, many of the drugs used to treat neurological disorders like MS and myasthenia gravis actively suppress the immune system, allowing for the possibility of more severe COVID-19 symptoms.

Some organizations specializing in neurological diseases warn that the drugs Azasan (azathioprine), CellCept (mycophenolate mofetil) or methotrexate combined with prednisolone may cause severe immunosuppression, making it all the more imperative to isolate oneself during the pandemic if you’re taking those drugs.

A Word From Verywell

Until scientists better understand COVID-19—including the ways in which it causes disease in different groups—anyone 65 and older or with a pre-existing health condition should be considered high risk.

Social distancing, frequent hand-washing, and staying at home are the best ways to reduce your risk during the pandemic. Moreover, early treatment at the first signs of illness (fever, cough, and shortness of breath) can ensure you are appropriately treated before an infection becomes severe.

Even if you are younger and have none of the risk factors outlined by the CDC, don't assume you are in the clear. If anything, taking the same preventive steps can reduce the spread of COVID-19 to other, more vulnerable populations.

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