How Does Obesity Affect COVID-19 Vaccine Immunity?

Key TakeawaysObesity is a risk factor for severe COVID infection, hospitalization, and death. This may be due to an impaired immune system.Historically, infectious disease vaccinations on people who are living with overweight or obesity have been less effective in preventing illness.Pfizer’s vaccine trials enrolled people with obesity and found the vaccine effective in this group.

Key Takeaways

Obesity is a risk factor for severe COVID infection, hospitalization, and death. This may be due to an impaired immune system.Historically, infectious disease vaccinations on people who are living with overweight or obesity have been less effective in preventing illness.Pfizer’s vaccine trials enrolled people with obesity and found the vaccine effective in this group.

It’s known that obesity can increase your risk of severe illness if you catch COVID-19, but does that also mean your weight could affect how well a vaccine can protect you from the virus?

Verywell asked several experts whether it’s possible that thePfizer and Moderna COVID-19 vaccinesmay not work as well in people who are living with overweight and obesity.

What Is Considered Obesity?

According to data from the World Health Organization (WHO), the number of people considered to be living with obesity jumped from 200 million in 1995 to 300 million in the year 2000.

Obesity: A Risk Factor for COVID-19

The Centers for Disease Control and Prevention (CDC) lists obesity as arisk factor for severe COVID-19illness, hospitalization, and death.

Aaron Eli Glatt, MD, FACP, FIDSA, FSHEA, the chair in the Department of Medicine and chief of Infectious Diseases and Hospital Epidemiologist at Mount Sinai South Nassau, tells Verywell that according to the CDC’s guidance, people with abody mass index (BMI)between 35 and 40 have a very severe risk for COVID-19. Even BMIs over 25 are considered high-risk.

An August 2020 study inObesity Reviewsfound that compared to people who were not living with obesity, people considered to be living with obesity:

The study also found that there was a 74% increase in thenumber of deaths from COVID-19in people who were living with obesity compared to people who were not living with obesity.

The Difference Between Overweight and Obesity

How Obesity Increases Risk

According to a study published in the journalDiabetes, Obesity, And Metabolismin September 2020, obesity’s role in increased mortality rates might be more prevalent in women than in men.

The COVID-19 pandemic itself might also be contributing to rising rates of obesity. A July 2020 article inNature Reviews Endocrinologyreported that emotional distress—with potential triggers being a declining economy, mandated lockdowns, and fear of infection—can prompt the brain to “emotionally eat” as a coping mechanism.

Obesity is multifactorial and can impact a person in many different ways. For one,excess weight can impair your breathingand the ability to take deep breaths.Nitin Desai, MD, CEO and CMO ofCOVID PreCheck,tells Verywell that it is challenging for people with obesity to be intubated and put on a ventilator because of their neck anatomy.

The Different Types of Obesity

Desai also says that people who are living with obesity often have other underlying health conditions as well. One example issleep apnea, which can cause low oxygen and pulmonary hypertension in severe cases. Obesity also increases the risk of other health conditions that can compromise immunity, like diabetes mellitus and heart disease.

Obesity and Immunity

Desai says that obesity has recently been recognized as a chronic disease rather than the state of a person’s weight. As with other chronic illnesses such as cancer, obesity can contribute to low resistance to infections.

Nitin Desai, MDThe data we have so far is from influenza, hepatitis B, and tetanus that shows people who are living with obesity have a decreased immune response to those vaccines.

Nitin Desai, MD

The data we have so far is from influenza, hepatitis B, and tetanus that shows people who are living with obesity have a decreased immune response to those vaccines.

“Adipose fat is considered like an endocrine organ now, and the immune response in central obesity is that the fat that sits around the organ and abdomen has a much higher prevalence of low immunity in fighting infection and generating antibodies to vaccines,” Desai says.

A 2012 review in theProceedings Of The Nutrition Societyreported that a potential mechanism could be that excess fat hinders access to the nutrients that immune cells need to carry out their daily activities.

How Vaccination Is Affected

Research has shown that obesity’s role in an impaired immune system often shows itself as lowered vaccine effectiveness. A 2017 study in the journalAnnals of the American Thoracic Societyfound that adults with obesity who were vaccinated with theflu shotwere two times more likely to get sick than vaccinated adults who were not living with obesity—despite having the same level of vaccine-induced antibodies.The researchers theorized that the effect might be related to impaired T cell function.

“The data we have so far is from influenza, hepatitis B, and tetanus that shows people who are living with obesity have a decreased immune response to those vaccines,” Desai says.

What Does COVID-19 Vaccine Efficacy Mean?

The Bottom Line

“I think the evidence strongly supports that it is effective in patients living with obesity, but I can’t guarantee that it’sas effectiveuntil we get a lot more data,” Glatt says.

Unlike the annual flu shot that uses a weakened or inactive version of the influenza virus, Pfizer and Moderna’s COVID-19 vaccines use mRNA technology. Desai says that this changes how the immune response is generated.

However, Desai personally thinks that people who are living with obesity will still respond poorly to the COVID-19 virus because of the body’s inability to handle the infection.

“It’s not how the immune challenge is administered whether through a vaccine or natural disease. The body’s response is weak irrespective of how the challenge is dealt,” Desai says. “People with obesity are most likely going to respond poorly whether it’s the vaccine or the virus. The coronavirus has already proven that it’s not good for obese individuals. In my opinion, no scientific evidence on this yet, [but] the vaccine will work more poorly in obese individuals.”

Obesity Prevention

By that logic, boosting your chances for vaccine effectiveness means controlling for obesity—but Glatt admits that’s easier said than done. “It’s a hard thing to accomplish, but it’s an important thing to accomplish.”

What This Means For YouIf you have overweight or obesity, you are more likely to get severely ill and experience complications if you get COVID-19. One of the best things you can do to help your immune system is work on losing weight, which would put you in a lower risk group. While experts are not sure whether the COVID-19 vaccines will be less effective in people with overweight or obesity, this has been the case for other types of vaccines in the past. Still, you should get a COVID-19 vaccine as soon as it becomes available and continue to take precautions like wearing a mask and social distancing.

What This Means For You

If you have overweight or obesity, you are more likely to get severely ill and experience complications if you get COVID-19. One of the best things you can do to help your immune system is work on losing weight, which would put you in a lower risk group. While experts are not sure whether the COVID-19 vaccines will be less effective in people with overweight or obesity, this has been the case for other types of vaccines in the past. Still, you should get a COVID-19 vaccine as soon as it becomes available and continue to take precautions like wearing a mask and social distancing.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit ourcoronavirus news page.

9 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.World Health Organization.Controlling the global obesity epidemic.Centers for Disease Control and Prevention.People With Certain Medical Conditions.Popkin BM, Du S, Green WD, Beck MA, Algaith T, Herbst CH, et al.Individuals with obesity and COVID‐19: A global perspective on the epidemiology and biological relationships.Obesity Reviews. 2020;21(11). doi:10.1111/obr.13128Peters SA, MacMahon S, & Woodward M.Obesity as a risk factor for COVID‐19 mortality in women and men in the UK biobank: Comparisons with influenza/pneumonia and coronary heart disease.Diabetes, Obesity and Metabolism,23(1), 258-262. doi:10.1111/dom.14199Stefan N, Birkenfeld AL & Schulze MB.Global pandemics interconnected — obesity, impaired metabolic health, and COVID-19.Nature Reviews Endocrinology, 1-15.Milner JJ, Beck MA.The impact of obesity on the immune response to infection.Proc Nutr Soc.2012;71(2), 298-306.Green WD & Beck MA.Obesity Impairs the Adaptive Immune Response to Influenza Virus.Ann Am Thorac Soc.2017;14(Supplement 5), S406-S409. doi:10.1513/AnnalsATS.201706-447AWPaich HA, Sheridan PA, Handy J, et al.Overweight and obese adult humans have a defective cellular immune response to pandemic H1N1 Influenza a virus.Obesity. 2013;21(11), 2377-2386.U.S. Food and Drug Administration (FDA).Pfizer-Biontech Covid-19 Vaccine (Bnt162, Pf-07302048) Vaccines And Related Biological Products Advisory Committee Briefing Document.

9 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.World Health Organization.Controlling the global obesity epidemic.Centers for Disease Control and Prevention.People With Certain Medical Conditions.Popkin BM, Du S, Green WD, Beck MA, Algaith T, Herbst CH, et al.Individuals with obesity and COVID‐19: A global perspective on the epidemiology and biological relationships.Obesity Reviews. 2020;21(11). doi:10.1111/obr.13128Peters SA, MacMahon S, & Woodward M.Obesity as a risk factor for COVID‐19 mortality in women and men in the UK biobank: Comparisons with influenza/pneumonia and coronary heart disease.Diabetes, Obesity and Metabolism,23(1), 258-262. doi:10.1111/dom.14199Stefan N, Birkenfeld AL & Schulze MB.Global pandemics interconnected — obesity, impaired metabolic health, and COVID-19.Nature Reviews Endocrinology, 1-15.Milner JJ, Beck MA.The impact of obesity on the immune response to infection.Proc Nutr Soc.2012;71(2), 298-306.Green WD & Beck MA.Obesity Impairs the Adaptive Immune Response to Influenza Virus.Ann Am Thorac Soc.2017;14(Supplement 5), S406-S409. doi:10.1513/AnnalsATS.201706-447AWPaich HA, Sheridan PA, Handy J, et al.Overweight and obese adult humans have a defective cellular immune response to pandemic H1N1 Influenza a virus.Obesity. 2013;21(11), 2377-2386.U.S. Food and Drug Administration (FDA).Pfizer-Biontech Covid-19 Vaccine (Bnt162, Pf-07302048) Vaccines And Related Biological Products Advisory Committee Briefing Document.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

World Health Organization.Controlling the global obesity epidemic.Centers for Disease Control and Prevention.People With Certain Medical Conditions.Popkin BM, Du S, Green WD, Beck MA, Algaith T, Herbst CH, et al.Individuals with obesity and COVID‐19: A global perspective on the epidemiology and biological relationships.Obesity Reviews. 2020;21(11). doi:10.1111/obr.13128Peters SA, MacMahon S, & Woodward M.Obesity as a risk factor for COVID‐19 mortality in women and men in the UK biobank: Comparisons with influenza/pneumonia and coronary heart disease.Diabetes, Obesity and Metabolism,23(1), 258-262. doi:10.1111/dom.14199Stefan N, Birkenfeld AL & Schulze MB.Global pandemics interconnected — obesity, impaired metabolic health, and COVID-19.Nature Reviews Endocrinology, 1-15.Milner JJ, Beck MA.The impact of obesity on the immune response to infection.Proc Nutr Soc.2012;71(2), 298-306.Green WD & Beck MA.Obesity Impairs the Adaptive Immune Response to Influenza Virus.Ann Am Thorac Soc.2017;14(Supplement 5), S406-S409. doi:10.1513/AnnalsATS.201706-447AWPaich HA, Sheridan PA, Handy J, et al.Overweight and obese adult humans have a defective cellular immune response to pandemic H1N1 Influenza a virus.Obesity. 2013;21(11), 2377-2386.U.S. Food and Drug Administration (FDA).Pfizer-Biontech Covid-19 Vaccine (Bnt162, Pf-07302048) Vaccines And Related Biological Products Advisory Committee Briefing Document.

World Health Organization.Controlling the global obesity epidemic.

Centers for Disease Control and Prevention.People With Certain Medical Conditions.

Popkin BM, Du S, Green WD, Beck MA, Algaith T, Herbst CH, et al.Individuals with obesity and COVID‐19: A global perspective on the epidemiology and biological relationships.Obesity Reviews. 2020;21(11). doi:10.1111/obr.13128

Peters SA, MacMahon S, & Woodward M.Obesity as a risk factor for COVID‐19 mortality in women and men in the UK biobank: Comparisons with influenza/pneumonia and coronary heart disease.Diabetes, Obesity and Metabolism,23(1), 258-262. doi:10.1111/dom.14199

Stefan N, Birkenfeld AL & Schulze MB.Global pandemics interconnected — obesity, impaired metabolic health, and COVID-19.Nature Reviews Endocrinology, 1-15.

Milner JJ, Beck MA.The impact of obesity on the immune response to infection.Proc Nutr Soc.2012;71(2), 298-306.

Green WD & Beck MA.Obesity Impairs the Adaptive Immune Response to Influenza Virus.Ann Am Thorac Soc.2017;14(Supplement 5), S406-S409. doi:10.1513/AnnalsATS.201706-447AW

Paich HA, Sheridan PA, Handy J, et al.Overweight and obese adult humans have a defective cellular immune response to pandemic H1N1 Influenza a virus.Obesity. 2013;21(11), 2377-2386.

U.S. Food and Drug Administration (FDA).Pfizer-Biontech Covid-19 Vaccine (Bnt162, Pf-07302048) Vaccines And Related Biological Products Advisory Committee Briefing Document.

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