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COVID-19 Resources

Obesity & COVID-19 Vaccine Effectiveness

Sep. 29, 2020

Rajat Madan, MD, UC Health infectious diseases specialist and assistant professor of Internal Medicine in the Department of Internal Medicine shares insight into the effectiveness of vaccines in obese adults. 


Will obesity block the effectiveness of a COVID-19 vaccine in the U.S.?

It has long been known by experts that those who have obesity are often unable to benefit from common vaccines, including influenza, hepatitis B and tetanus. When a COVID-19 vaccine is discovered, how will the obese population be impacted? Will they benefit from a vaccine or will they be vulnerable to infection and illness?

With a vaccine trial now underway at the University of Cincinnati and UC Health, and knowing that more than 107 million adults in the U.S. are obese, can our nation beat this virus despite the availability of a vaccine?

Rajat Madan, MD, UC Health infectious diseases specialist and assistant professor in the Department of Internal Medicine at the UC College of Medicine, is available to discuss and clarify information about this topic, which includes addressing the questions listed below.

What is a simple explanation about how vaccines work and why obesity often interferes with the body’s immune response?

Vaccines are made up of small parts of a virus (e.g. viral proteins) or dead virus particles. Our body’s immune system recognizes these as foreign materials and generates a protective immune response against them. When a vaccinated person’s immune system then sees the whole virus, it generates the same immune response, which results in killing the virus. Obesity affects many facets of our immune system and results in dysregulated immune responses. Therefore, the effects of vaccination in an obese person can be very different, compared to a non-obese person.

If obesity impacts the effectiveness of a vaccine, such as the flu shot, will a COVID-19 vaccine be any different?

Typically, obese individuals have a poor response to the flu vaccine. However, at this time, we do not know if the effectiveness of a COVID-19 vaccine will be different in obese individuals or not. This is because some of the vaccines that are currently being developed for COVID-19 use a new technology – “mRNA” vaccines – and therefore, the responses could be different.

With our nation’s high level of obesity, how is bariatric surgery helpful in the battle against this epidemic?

Bariatric surgery is a very effective option for the treatment of obesity. However, it takes weeks to see maximal weight loss. While it likely does not have a direct role in battling the epidemic, in the long run, reducing the overall burden of obesity in our society could have an impact on decreasing the severity of the epidemic. 

When is surgery safer than remaining obese? Why?

In cases of morbid obesity (i.e. people with a BMI > 40) and in patients with conditions that are associated with worse obesity-associated outcomes, such as high blood pressure or uncontrolled diabetes, getting surgery is better than remaining obese. Surgical weight loss in these patients has been shown to reverse these other chronic conditions and therefore, giving patients better outcomes.

What is the most important message that those with obesity should hear in today’s COVID-19 world?

Obesity is an independent risk factor for having worse outcomes after COVID-19. Therefore, prevention is imperative in obese individuals and they should be especially careful about social distancing and trying to maintain a healthy lifestyle.