Could Obesity Make a COVID-19 Vaccine Less Effective?

Research suggests weight may play a role in whether a coronavirus vaccine works. We asked Dr. Rodrigo Barros to explain.

by Sarah Ellis Health Writer

Talk of a future COVID-19 vaccine is everywhere right now. Drug companies are racing to be the first to get their product to market: A whopping 212 vaccines are currently in development around the world and 34 are in one of four phases of clinical trials. By some estimates, a COVID-19 vaccine could be available by early next year.

But here’s something that might warrant further consideration: What if the vaccine works differently in different bodies? Specifically, what if it doesn’t work the same in people who are slim versus those who are obese or overweight? According to the Centers for Disease Control and Prevention (CDC), 42% of American adults are obese. Research shows that obesity contributes to a higher death rate from cardiovascular disease, diabetes, cancer, and other chronic conditions. It’s also a risk factor for serious COVID-19 complications and can impact the body’s immune response—an important element in how vaccines work.

A September 2020 report in Endocrinology hypothesized that obesity might impact the efficacy of vaccine treatments for COVID-19. To get clarity on what this could mean, we spoke with Rodrigo Barros, M.D., Ph.D., an obesity expert who works at the State Institute of Diabetes and Endocrinology (IEDE) in Rio de Janeiro, Brazil.

HealthCentral: How does obesity affect the immune system?

Dr. Rodrigo Barros: Obesity is associated with several autoimmune and inflammatory diseases, such as type 2 diabetes, non-alcoholic fatty liver disease, asthma, rheumatoid arthritis, osteoarthritis, allergy, atopic dermatitis, and even cancer and multiple sclerosis.

Here’s how it works: Fat tissue, also known as adipose tissue, is very important for energy storage and whole-body metabolism. Fat tissue is composed of fat cells (adipocytes) and many immune cells (macrophages, neutrophils, mast cells, eosinophils, T and B cells). When someone gains weight and accumulates fat, oxygen levels go down in the adipose tissue, causing stress and death of adipose cells. Dead cells release substances that attract macrophages (special immune cells that destroy pathogens), which invade the adipose tissue and cause chronic inflammation. This decreases the body’s ability to fight an infection, such as a virus.

HC: Has obesity been shown to alter the effectiveness of vaccines?

RB: Yes. Researchers from the University of North Carolina at Chapel Hill have shown that obese adults vaccinated for influenza are twice as likely to develop influenza and influenza-like illness as healthy weight adults. The authors believe that in obese patients, an immune cell called “T cell” is activated less when stimulated by the influenza vaccine. They conclude that obesity reduces the effectiveness of that vaccine. We can speculate that a similar response would happen in a new COVID-19 vaccine.

HC: How excactly might obesity affect a COVID-19 vaccine response?

RB: Obese people who have COVID-19 have an altered inflammatory response. The more affected the inflammatory response is, the more severe the disease is. COVID-19 is a new disease, and researchers still have a long way to understanding how the virus works in our body. More work needs to be done to better understand COVID-19 response in obese patients, which may help develop safer vaccines and therapies. We don’t know the specifics yet, but this is an important and necessary line of research.

HC: What can people with obesity do to minimize their risk of COVID-19 complications?

RB: It is very important that people with obesity keep as healthy as possible. A daily workout routine and healthier diet can help the immune system fight COVID-19. We also know that obese people who have uncontrolled disease, especially type 2 diabetes, are at greater risk if they contract the virus. Keeping sugar levels under control is the best way to prevent complications.

Also, practice self-isolation when possible, keep your hands clean, and avoid touching your eyes, nose, and mouth. If you haven’t seen your health care providers in a while, now is a good time to talk to them and ask for some advice. Unfortunately, until a vaccine is available, prevention is the best medicine.

Sarah Ellis
Meet Our Writer
Sarah Ellis

Sarah Ellis is a wellness and culture writer who covers everything from contraceptive access to chronic health conditions to fitness trends. She is originally from Nashville, Tennessee and currently resides in NYC. She has written for Elite Daily, Greatist, mindbodygreen and others. When she’s not writing, Sarah loves distance running, vegan food, and getting the most out of her library card.