Obesity as a Major Risk Factor for COVID-19

Soon after COVID-19 became entrenched in the population, it became apparent that certain individuals were at greater risk for serious or fatal outcomes from the disease than others. Patients with obesity, and particularly those with severe obesity, were among those faring the worst. In one study, patients with a body mass index (BMI) of 30 or higher were found to be at significantly increased risk for severe COVID-19, and those with a BMI of 35 and higher had a dramatically increased risk of death. Another found severe obesity to be a profound risk factor for death from COVID-19 in men age 60 and younger. Meta-analyses confirmed these findings.

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With no cure for the virus in sight and the prospect of a vaccine still months away, it is more important than ever for physicians to keep a close eye on patients with obesity, says Ali Aminian, MD, Director of the Bariatric & Metabolic Institute at Cleveland Clinic.

“Discontinuity of care may lead to weight gain in this unprecedented time,” he says. “Ideally, there should be no interruption in behavioral support or medical treatment of obesity. Plans for bariatric surgery should move ahead.”

Fear the worst

A unique feature of SARS-CoV-2 infection is the wide spectrum of presentation. Some infected individuals remain asymptomatic or experience only mild symptoms. Others, including those with obesity, are prone to developing serious illness and succumbing to the disease.

“In the past six months we have learned that obesity is a risk factor for the severe form of COVID-19 and associated hospital admission, need for intensive care, use of vasopressors and ventilator support, and increased mortality,” says Dr. Aminian.

Potential explanations

Why patients with obesity are seriously impacted by SARS-CoV-2 is unknown, but Dr. Aminian offers several explanations.

Underlying cardiovascular risk. Patients with obesity frequently have underlying cardiovascular disease and its risk factors, including hypertension, diabetes, coronary artery disease and heart failure. Presence of these underlying conditions can lead to poor outcomes after SARS-CoV-2 infection.
Poor pulmonary reserve. The mechanical impact of excess weight on the function of the chest wall and diaphragm, and common presence of other lung conditions such as sleep apnea, obesity hypoventilation syndrome and asthma, weaken cardiopulmonary reserve and increase the risk of pulmonary manifestations of COVID-19.
Increased risk of thrombosis. Obesity is a pro-coagulant condition and increases the risk of venous thromboembolism. “The SARS-CoV-2 virus damages the endothelium, increasing the risk of blood clots,” says Dr. Aminian. “Autopsies have revealed that widespread severe endothelial injury and blood clots are responsible for increased mortality in many patients with SARS-CoV-2 infection.”
Impaired immunity. Obesity and diabetes impair innate and adaptive immune responses to infections.
Overactive immune response. Obesity is a chronic inflammatory state that causes excessive cytokine production. Infection with the SARS-CoV-2 virus also triggers the immune system to release cytokines, which can lead to a cytokine storm that damages organs. “This may partly explain the severity of infection in patients with obesity,” says Dr. Aminian.

Protecting patients now

To decrease the risk of COVID-19, physicians should make sure patients with obesity understand their excess risk and the need to take precautions.

“This pandemic has shown how patients with obesity, particularly severe obesity, are vulnerable to infection with the virus,” he says. “It is important these individuals follow public health recommendations for masking, social distancing and handwashing.”

For protection later

Making a habit of self-protection practices may be a lifesaver in the long run. While the world looks forward to being freed from COVID-19 constraints by a vaccine, patients with obesity may not enjoy the same protection.

“Previous experience has shown that patients with obesity may not have an adequate immunological response after vaccination. This may present a challenge for them when a COVID-19 vaccine is developed,” says Dr. Aminian.

Bariatric and metabolic surgery, which provides substantial and sustained weight loss, may be the best—if not only—long-term solution.

“We do not know if there is a cutoff weight at which risk of COVID-19 drops dramatically. We do know that when patients with obesity lose at least 5% to 10% of their weight, their risk of cardiovascular disease drops and survival improves. Patients will be healthier after losing a large amount of their excess weight,” he explains.

“We suggest patients with obesity consider weight-loss surgery. But for now, in this stage of the pandemic, our advice is that physicians, dietitians and other health care providers stay in touch with their patients to ensure their weight-loss efforts remain on track and emphasize their need to take extra precautions to prevent coronavirus exposure.”