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Extra weight impairs the body's immune response to COVID-19

A recent study led by the University of Queensland has confirmed that being overweight impacts the body’s immune response to SARS-CoV-2, the virus responsible for COVID-19

This research was led by Marcus Tong, a PhD candidate in the School of Chemistry and Molecular Biosciences. The study provides crucial information for shaping future policies, particularly concerning vaccination and public health strategies.

Impaired antibody response 

The findings are primarily focused on the distinction between the body’s response to SARS-CoV-2 infection and its response to COVID-19 vaccination in overweight individuals. 

“We’ve previously shown that being overweight – not just being obese – increases the severity of SARS-CoV-2,” said Tong. “But this work shows that being overweight creates an impaired antibody response to SARS-CoV-2 infection but not to vaccination.”

Focus of the study 

The research highlights a critical differentiation in how the body’s immune system reacts to the virus naturally versus through the aid of vaccines.

To reach these conclusions, the experts collected and analyzed blood samples from individuals who had recovered from COVID-19. The participants were not reinfected during the study period, which spanned approximately 3 months and 13 months post-infection. 

Critical insights 

“At 3 months post-infection, an elevated BMI was associated with reduced antibody levels,” explained Tong. “And at 13 months post-infection, an elevated BMI was associated with both reduced antibody activity and a reduced percentage of the relevant B cells, a type of cell that helps build these COVID-fighting antibodies.”

By contrast, the experts found that an elevated BMI did not affect the antibody response to the COVID-19 vaccination. This was observed approximately 6 months after the administration of the second vaccine dose. 

This insight is particularly significant as it suggests that vaccination can offer effective protection against COVID-19 for overweight individuals, despite their impaired natural immune response to the virus.

Increased risk of reinfection 

Professor Kirsty Short, commenting on the implications of these findings, emphasized the need for tailored health policies. 

“If infection is associated with an increased risk of severe disease and an impaired immune response for the overweight, this group has a potentially increased risk of reinfection,” explained Dr. Short. “It makes it more important than ever for this group to ensure they’re vaccinated.”

Public health 

Dr. Short said that from a public health perspective, this data draws into question policies around boosters and lockdowns.

“We’d suggest that more personalized recommendations are needed for overweight people, both for ongoing COVID-19 management and future pandemics.”

“Finally, the data provides an added impetus to improve SARS-CoV-2 vaccination in low-income countries, where there’s a high percentage of people who are overweight and are dependent on infection-induced immunity,” said Dr. Short.

Study implications 

The study not only sheds light on the immediate concerns of managing COVID-19 but also underscores the broader implications for global health, particularly in low-income countries. 

These regions, characterized by a high percentage of overweight individuals who rely on infection-induced immunity, face unique challenges in ensuring adequate SARS-CoV-2 vaccination coverage.

The research is published in the journal Clinical & Translational Immunology.

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