Studies begin to untangle obesity’s role in COVID-19
By Katherine J. Wu
In early April, Edna McCloud woke up to find her hands tied to her hospital bed.
She had spent the past four days on a ventilator in a hospital in St. Louis County, Missouri, thrashing and kicking under sedation as she battled a severe case of COVID-19.
“They told me, ‘You were a real fighter down there,’” recalled McCloud, a 68-year-old African American retiree with a history of diabetes and heart problems. She weighed close to 300 pounds when she caught the coronavirus, which ravaged her lungs and kidneys. Nearly six months later, she feels proud to have pulled through the worst. “They said people with the conditions I have, normally, this goes the other way,” she said.
As rates of obesity continue to climb in the United States, its role in COVID-19 is a thorny scientific question. A flurry of recent studies has shown that people with extra weight are more susceptible than others to severe bouts of disease. And experiments in animals and human cells have demonstrated how excess fat can disrupt the immune system.
But the relationship between obesity and COVID-19 is complex, and many mysteries remain. Excess weight tends to go hand in hand with other medical conditions, like high blood pressure and diabetes, which may by themselves make it harder to fight COVID-19. Obesity also disproportionately affects people who identify as Black or Latino — groups at much higher risk than others of contracting and dying from COVID-19, in large part because of exposure at their workplaces, limited access to medical care and other inequities tied to systemic racism. And people with extra weight must grapple with persistent stigma about their appearance and health, even from doctors, further imperiling their prognosis.
“A new pandemic is now laying itself on top of an ongoing epidemic,” said Dr. Christy Richardson, an endocrinologist at SSM Health in Missouri. Regarding obesity’s effects on infectious disease, she said, “We are still learning, but it’s not difficult to understand how the body can become overwhelmed.”
The correlations between COVID-19 and obesity are worrisome. In one report published last month, researchers found that people with obesity who caught the coronavirus were more than twice as likely to end up in the hospital and nearly 50% more likely to die of COVID-19. Another study, which has not yet been peer-reviewed, showed that among nearly 17,000 hospitalized COVID-19 patients in the United States, more than 77% had excess weight or obesity.
Experts said part of obesity’s threat is mechanical: Large amounts of fat, for instance, can compress the lower parts of the lungs, making it harder for them to expand when people breathe in. The blood of people with obesity also seems to be more prone to clotting, plugging up delicate vessels throughout the body and starving tissues of oxygen.
Fat, or adipose tissue, can also send out hormones and other signals that make nearby cells go haywire. “Adipose tissue is very active,” said Rebekah Honce, a virologist at St. Jude Children’s Research Hospital in Tennessee and an author on a recent review describing how metabolism intersects with immunity. “It’s not a dormant tissue.”
One of fat’s most potent effects appears to involve quelling the body’s initial immune response to the virus, allowing the pathogen to spread unchecked.
Eventually, the body’s immune soldiers get their act together. But this delayed assault might do more harm than good: When late-arriving immune cells and molecules finally rouse themselves into action, they go berserk, driving uncontrolled bouts of inflammation throughout the body.
These aberrant early responses can have severe long-term consequences as well, said Melinda Beck, who studies how nutrition affects immunity at the University of North Carolina at Chapel Hill. The constant inflammation, she said, can wear away at the immune system’s ability to generate a long-lived population of “memory” cells, which store intelligence about past encounters with pathogens.
Similar trends have been noted in the immune systems of elderly patients, who also struggle to marshal effective defenses against pathogens. When obesity enters the picture, Beck said, some of the immune cells found in 30-year-old people “look like those of an 80-year-old.”
These problems could have a big impact on the first coronavirus vaccines, Beck said. If the immune systems of people with obesity are more prone to pathogen amnesia, then they may need different dosages of a vaccine. Some products might not work at all in people carrying extra weight.
Like many other conditions that can exacerbate COVID-19, excess weight does not have a quick fix — especially in areas where access to healthy food and opportunities for exercise are vastly uneven among communities.
“If we don’t address these social underpinnings, I think we’ll continue to see a recurrence of what is happening now,” said Dr. Jennifer Woo Baidal, a pediatric weight management specialist at Columbia University.
In her neighborhood in St. Louis County, where there have been more than 23,000 cases of the coronavirus since March, McCloud has struggled to find fresh, affordable produce at her local grocery store. Availability has plummeted further since the start of the pandemic, she said, and what little is on the shelves is often on the verge of rotting.
A few months after McCloud got sick, her younger sister, Elaine Franklin, 62, began to experience terrible headaches. When she spoke to family members, they asked why she sounded so out of breath. “My son said, ‘Mama, you need to go to urgent care,’” Franklin recalled. A test soon revealed that she, too, had caught the coronavirus.
Franklin’s case of COVID-19 was more moderate than her sister’s. But she still deteriorated quickly, to the point where she could no longer reach the bathroom without assistance. “I was so weak, I couldn’t balance myself,” she said.
Her physical symptoms haven’t been the only hardship. Franklin, who is overweight, said she had been irritated by incessant messaging in news reports blaming illnesses like hers on excess fat.
“The way they were saying it is that because you’re obese and didn’t take care of yourself, you’ll get this disease,” Franklin said. “I feel like that was unfair.”
Even medical professionals show bias when caring for patients with excess weight, said Dr. Benjamin Singer, a pulmonologist at the University of Michigan and an author on a recent review of obesity’s influence on immunity. Studies have shown that doctors tend to be more dismissive of patients with obesity and may brush off worrisome symptoms as irrelevant side effects of their weight. Drug dosages and diagnostic machines are also often incompatible with patients carrying excess weight, making it difficult to tailor treatments. Such interactions can be a powerful disincentive to some of the people who most need care.
“These are not easy conversations,” said Dr. Kanakadurga Singer, a pediatric endocrinologist at the University of Michigan. (She and Benjamin Singer are married.) Not everyone who weighs more than average is unwell, she said. “It’s more than just the numbers, and it’s not just the weight we should focus on.”
In St. Louis County, McCloud and Franklin have recovered well, although both sisters still grapple with lingering symptoms. McCloud has occasional fatigue and an intermittent cough. “I can’t talk like I did before,” she said. Franklin’s headaches never disappeared, and her mind now feels constantly clouded by a fog.
Both women have worried about their sons, who also developed COVID-19. Chris McCloud, a teacher, was like his mother put on a ventilator and spent several weeks in the hospital shortly before Edna McCloud fell ill. He was overweight as well.
Franklin suspects she might have contracted the coronavirus from her son Darren Catching, who most likely caught it from a former co-worker. He had recently lost a large amount of weight, Franklin said, and was not hospitalized either, instead recovering at home.
In July, when she was infected, she sought medical attention twice. She had lupus, an autoimmune disease, and worried that she wouldn’t be able to fight off the virus. Thoughts of friends and acquaintances who had died from COVID-19 rushed through her head.
But both times, Franklin was sent home — first from an urgent care facility and then from a hospital emergency room.
She managed to heal on her own, she said. Still, she wonders if her weariness and brain fog might have been prevented by more attentive clinical care. “I’m not a doctor or anything,” she said. “But if I had been in the hospital, maybe it would have been better.”