Is Obesity A Risk Factor For More Severe COVID-19 Infection?

The data on COVID-19 (coronavirus) is rapidly emerging. The global health care community is working hard to try to understand the risk factors for more severe illness. One question that has been asked is whether obesity is a risk factor for more severe illness.

Severe COVID-19 infection is characterized by pneumonia, which can lead to trouble breathing, and in the most severe cases, can lead to acute respiratory distress syndrome (ARDS), where a powerful inflammatory response in the lungs makes the lungs less able to bring oxygen into our blood stream. The inflammatory response to COVID-19 can also result in the compromise of other organ systems, including the heart, kidneys, and other vital organs. COVID-19 pneumonia can also lead to coinfection with secondary bacterial pneumonia.

What is apparent so far is that the following groups of people are at higher risk of severe infection:

older people
people with heart disease
people with diabetes
people with chronic lung disease
people with high blood pressure
people with cancer

Emerging data suggests that obesity is also a risk factor for more severe disease. In a report of 112 patients in China with cardiovascular disease who were admitted to hospital for COVID-19 infection, they looked at the body mass index (BMI) of those who died and those who lived. Of the 17 people who died, 15 (88%) had a BMI over 25. Of the 95 patients who survived, only 18 (19%) had a BMI over 25. Said another way, 45% of the people who had a BMI over 25 died, whereas only 3% of people with a BMI under 25 died.

(note that while the World Health Organization generally considers overweight to be defined as a BMI of 25 or greater, and obesity to be defined as a BMI of 30 or greater, China (as well as several other countries) use lower BMI criteria)

We likewise learned during the H1N1 influenza pandemic in 2009 that obesity was a risk factor for hospitalization and death.

So why would people with obesity be at higher risk of more severe disease? Well, we know that people who carry excess weight have a higher risk of compromised lung function. Reasons for this include a high prevalence of obstructive sleep apnea, obesity hypoventilation syndrome, higher risk of asthma, and excess weight compressing the lungs, making lung volumes smaller. People with obesity are also at higher risk of coronary artery disease and congestive heart failure, which can impair oxygen exchange as well. Many people with obesity also have one or several of the risk factors listed above, such as diabetes or high blood pressure.

We also know that there is a state of chronic low grade inflammation in obesity, and it has been hypothesized that this inflammatory state may increase the risk of a more severe inflammatory reaction in the lungs when infection hits.

So, what can we do about this? Avoiding infection is paramount. As noted in last week’s blog post (which was directed towards people with diabetes but contained much general information):

Social distancing: keep your distance from others. I can’t stress this enough.
Thorough handwashing with soap and water kills the virus. Alcohol based hand rubs are also useful.
Cover your mouth and nose with your elbow or a tissue when you cough or sneeze. Avoid touching your mouth, face or eyes.
Avoid travel.
Self isolate for 14 days if you have returned from out of country – note that this is a global travel advisory that is mandatory in Alberta.
Make sure your other vaccinations are up to date (including influenza and pneumococcus).
Attention to nutrition and adequate protein intake is important.
Exercise is good to maintain health, but do it at home: there are lots of apps and online videos that you can use for guidance and motivation.

Sending much love and support to everyone around the world during this terribly challenging time. Working together to minimize spread is the best thing we can do.

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