Why Comorbidities Are a Risk Factor for Severe COVID-19

Comorbidities can affect the course of COVID-19—here's why.

When vaccines for COVID-19 first became available, states prioritized at-risk populations, including people with comorbidities and underlying conditions. Certain people with comorbidities were eligible to receive the vaccine before others to provide extra protection to those who were more likely to experience severe cases of COVID-19 or death.

But, what are comorbidities—and how do they affect COVID-19? Here's what experts told us, plus how to know if you have one.

Comorbidities Definition

"Comorbidities are the presence of two or more diseases in the same person," Jooby Babu, MD, pulmonologist and critical care specialist at Providence St. Joseph Hospital in Southern California, told Health. "For instance, a person who has diabetes and hypertension, or diabetes and kidney failure."

The term comorbidity was first documented in the 1970s by the renowned doctor and epidemiologist A.R. Feinstein, who used the term when referring to people who suffered from rheumatic fever and multiple other diseases.

How Do Comorbidities Affect COVID-19?

A disease weakens the body's systems, making it difficult for the body to eliminate the cause of the disease and to fight invaders, like viruses and bacteria. When two or more conditions are present at the same time, this can be very taxing on the body, and the affected person may need longer to recover than someone who does not have comorbidity.

After the start of the pandemic, researchers began studying the link between people with certain comorbidities and the COVID-19 disease. In September 2020, a study published in PLoS Medicine examined more than 31,000 adult patients in the US and found that comorbidities with COVID-19 put people at a higher risk of mortality.

Comorbidities are a serious health concern, said Dr. Babu, because the presence of two or more conditions increases the chances of hospitalization and the risk of death and affects quality of life. When a person experiences comorbid conditions, they may have a compromised immune system or need additional care that exposes them to others. Plus, they may already be experiencing complications from the underlying condition that puts increased stress on their body. According to a study published by the Annals of Family Medicine, "Comorbidity is associated with worse health outcomes, more complex clinical management, and increased health care costs."

CDC List of Comorbid Conditions

The Centers for Disease Control and Prevention (CDC) provides a list of comorbid conditions in COVID-19 patients, which includes cancer, chronic kidney disease, chronic lung disease, heart disease, Down syndrome, obesity, pregnancy, and type 1 and 2 diabetes mellitus.

A July 2021 study conducted by the CDC involving more than 500,000 patients hospitalized with COVID-19 from March 2020 to March 2021 identified several risk factors for death. The strongest were obesity, anxiety and fear-related disorders, and diabetes with complications. It also found that risk increases with the number of comorbidities.

Comorbidities and the COVID-19 Vaccine

The opportunity to get the COVID-19 vaccine came as welcome news to those who live with chronic health conditions. For Dr. Babu, it was an important development. "Patients with comorbidities should get vaccinated as early as possible," said Dr. Babu.

Vaccination against COVID-19 is also effective in breakthrough infections. A breakthrough infection is when someone who is fully vaccinated contracts the disease. Vaccination can decrease the severity of COVID-19 and hospitalizations, as was seen in the results of a December 2021 study published in JAMA Internal Medicine that examined electronic medical record data from a large US sample of vaccinated immunocompromised individuals.

Whether you've been vaccinated or not, if you live with a chronic health condition, it's even more important that you follow the hygiene and safety guidelines set out by the CDC. In other words, limit person-to-person contact, wear masks in public areas, and be super vigilant about handwashing with soap and water or using hand sanitizers.

It's also important to reduce the risk of medication interactions, so if you live with multiple conditions or disorders, make sure your doctor knows all prescribed meds and over-the-counter drugs you're taking.

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