Higher BMI Linked to Increased Risk of SARS-CoV-2 Infection

The 2019 coronavirus disease (COVID-19), caused by the severe acute respiratory syndrome coronavirus (SARS-CoV-2), causes serious illness in high-risk populations. These include the elderly and those with underlying health conditions such as diabetes, hypertension, heart disease and obesity.

Researchers from the University of Miami Miller School of Medicine, USA, have revealed that the spike-specific immunoglobulin G antibodies in obese people are negatively associated with the body mass index (BMI) and serum levels of pro-inflammatory and metabolic markers of pneumonia.

The study, published in the pre-print journal medRxiv *, also found that a higher BMI is linked to a higher infection rate with SARS-CoV-2.

Obesity and COVID-19

The SARS-CoV-2 is actively spreading worldwide. It has infected more than 78 million people and killed more than 1.71 million people. Information on human immune responses to SARS-CoV-2 infection is limited.

However, recent studies have shown that some people are more likely to get infected and develop a more serious illness than others. Older adults and those with co-morbidities are more likely to develop severe COVID-19. Recently, studies have also shown that obesity can predispose a person to severe COVID-19.

Recently published data showed that chronic low-grade systemic inflammation, called inflammation, is the main cause of the cellular and molecular changes induced by SARS-CoV-2. It is also responsible for the highest death rates.

Persistent local and systemic inflammation caused by obesity contributed to immune cell destruction and decreased immunity.

The inflammation found in obese individuals leads to several debilitating chronic diseases, including cancer, atherosclerosis, type 2 diabetes and inflammatory bowel disease. Obesity is an additional risk factor for severe COVID-19.

The study

To arrive at the study results, the researchers evaluated the effects of obesity on the secretion of SARS-CoV-2-specific IgG antibodies in the blood of COVID-19 patients.

The team measured serum levels of SARS-CoV-2 Spike-specific IgG antibodies in lean and obese COVID-19 patients, as well as uninfected controls, using an enzyme-linked immunosorbent assay (ELISA).

First, the study found that BMI was higher in positive SARS-CoV-2 patients compared to non-infected controls. This suggests that a higher BMI is associated with severe respiratory symptoms. During hospitalization, people with a higher BMI have severe respiratory symptoms such as cough, fever, shortness of breath and hypoxia or low oxygen levels.

The study’s findings also showed that spike-specific IgG antibodies in obese people are negatively linked to BMI and serum levels of pro-inflammatory and metabolic markers of inflammation and pneumonia.

The data collected could help develop an inflammatory signature with a strong predictive value for immune dysfunction, which can be used as a therapeutic target to enhance humoral immunity in obese people.

Another result of the current study is the negative association of SARS-CoV-2 IgG antibodies with markers of pneumonia (SAA, CRP, ferritin) in our cohort of COVID-19 patients, ”the researchers explained.

“These are important inflammatory mediators and markers of inflammatory lung damage in patients with the catastrophic acute respiratory distress syndrome, which is a primary consequence of COVID-19,” she added.

The research results support that SARS-CoV-2 infection, similar to influenza, can cause the degradation of self-tolerance to autoantigens in obese people. It is essential to consider them as a high-risk group, with a higher chance of developing serious symptoms because of COVID-19.

In addition, the quality of the antibody response in obese COVID-19 patients is crucial for future vaccination efforts to prevent SARS-CoV-2 infection and COVID-19-associated complications. Obese people may also benefit from being among the first to get a vaccination.

*Important announcement

medRxiv publishes preliminary scientific reports that are not peer-reviewed and therefore should not be considered conclusive, serve clinical practice / health-related behavior, or be treated as established information.