Obesity has been linked to the development of severe coronavirus disease (COVID-19) caused by severe coronavirus 2 with acute respiratory syndrome (SARS-CoV-2). With an estimated 1.9 billion people overweight or obese worldwide, the impact on morbidity and mortality of the coronavirus pandemic is significant.
A new study by researchers at Harvard Medical School and the Ragon Institute of MGH, MIT and Harvard showed that obesity is not linked to an increased risk of SARS-CoV-2 infection. However, the team showed that obesity is linked to increased manifestations of symptoms in mild COVID-19 infections, suggesting that obesity affects the pathophysiology of COVID-19.
The study published as a pre-print on the medRxiv * server shows the risk of SARS-CoV-2 infection in obese patients. Previous infection studies have shown that obese people with a body mass index (BMI) of 30 or more have a higher risk of infection.
With previous viral pathogens like influenza A (H1N1) during the 2009 pandemic, obese people were more likely to be hospitalized, need intensive care assistance, and die of the infection. Obesity is also linked to a weaker immune response after natural influenza or flu infection.
Aside from the association between obesity and clinical outcomes, evidence shows an association between a higher BMI and a higher incidence of COVID-19 disease, suggesting that BMI may increase susceptibility to infection. However, there is limited data to support this link.
To reach the results of the study, the researchers performed a serial serological assessment to determine the immune epidemiology of SARS-CoV-2 infection in workers in industry, which included staff from Space Exploration Technologies Corporation.
A total of 4,469 participants were enrolled in the study at work locations in California, Washington, Texas, and Florida. The duration of the study began on April 20 and ended on July 28. The researchers collected blood samples and intermediate symptom reports every month.
Limited influence of BMI on SARS-CoV-2 antibody profiles (n = 77). (A) The dot plots show similar mean fluorescence intensity levels of IgG1, IgM, IgG3 and IgA levels in subjects classified as normal weight (n = 29), overweight (n = 23) and obesity (n = 25). (B) The uniform manifold and projection (UMAP) shows the relationship between antibody profiles and BMI (point size, color intensity) and underlines the limited influence of BMI on the design of SARS-CoV-2 antibody responses. (C) Correlation diagram of Figure 13 shows a limited correlation between BMI and 20 immunological traits.
What the study found
The researchers reported in the study that 7.21 percent of the participants were seropositive. Obesity was associated with increased reporting of fever and other symptoms. However, there were no differences in immune response between normal weight and overweight or obese individuals.
“We present benchmark data that obesity is not associated with an increased risk of SARS-CoV-2 infection. This symptom phenotype is strongly influenced by obesity. and that despite evidence of obesity-related immunodeficiency in severe infections, ”the team explained.
“There is no evidence of a suppressed or impaired immune response with multiple immune measures in non-severe infections,” they added.
However, the team emphasized that not only is a known measure of serious illness such as hospitalization, ICU admissions, and death from COVID-19 more common in overweight people, but that obesity is also a major contributor to being symptomatic in mild to moderate illness .
However, the study has limitations. First, the study population was overrepresented industrial workers compared to the total population of the United States. For example, many employees were Hispanic, male and younger, with fewer comorbidities, including obesity.
Obesity and COVID-19 vaccine
Health experts fear that obese people may not respond to future SARS-CoV-2 vaccines compared to others. It has long been known that people with obesity often cannot benefit from popular vaccines such as hepatitis B, tetanus, and influenza vaccines.
Vaccines are made up of dead virus particles, or virus proteins, to trigger an immune response in the body. The immune system recognizes these particles as foreign invaders and creates a protective immune response against them.
Obesity affects the immune system in many ways and leads to impaired immune responses. Therefore, the effects of vaccination on an overweight person may be different from those who are not.
* Important NOTE
medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be considered conclusive, guide clinical practice / health-related behavior, or treated as established information.