Being overweight can impair the body’s antibody response to SARS-CoV-2 infection but not to the protection offered by vaccination, a new research has revealed.

The research, published in the journal Clinical & Translational Immunology, was led by the University of Queensland.

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

The team collected blood samples from people who had recovered from COVID-19 and had not been reinfected during the study period, approximately 3 months and 13 months post-infection.

“At 3 months post-infection, an elevated BMI was associated with reduced antibody levels,” Tong said.

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.

In contrast, an elevated BMI had no effect on the antibody response to COVID-19 vaccination at approximately 6 months after the second vaccine was administered.

Associate Professor Kirsty Short said the results should help shape health policy moving forward.

“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,” Dr Short said.

“It makes it more important than ever for this group to ensure they’re vaccinated.”

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

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