Being overweight hampers body's immune response to Covid infection: Study

Obesity weakens the antibody response to SARS-CoV-2 infection, but not to the COVID-19 vaccine, according to a study. Increased BMI reduces antibody levels and activity after infection. The corresponding percentage of B cells also decreases. Obese people have a greater risk of reinfection, which emphasises the importance of vaccination. Individual recommendations and better vaccination measures are needed for overweight people. Low-income countries with a high percentage of overweight people should prioritise vaccination.

New Delhi:Being overweight can impair the body's antibody response to SARS-CoV-2 infection but not to the protection offered by COVID-19 vaccination, according to a study.

The finding, published in the journal Clinical & Translational Immunology, builds on the team's existing research on how COVID-19 affects people who are overweight.

"We have previously shown that being overweightnot just being obeseincreases the severity of SARS-CoV-2," said Marcus Tong, a Ph.D. candidate at the University of Queensland in Australia. "But this work shows that being overweight creates an impaired antibody response to SARS-CoV-2 infection but not to vaccination," Tong said.

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

"At three months post-infection, an elevated BMI was associated with reduced antibody levels," Tong said. "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," he added.

The body mass index (BMI) is defined as the body mass divided by the square of the body height. In contrast, an elevated BMI had no effect on the antibody response to COVID-19 vaccination at approximately six months after the second vaccine was administered, the researchers said.

According to Kirsty Short, Associate Professor at the University of Queensland, 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," Short said. "It makes it more important than ever for this group to ensure they're vaccinated," she added.

The researchers noted that 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," Short said.

"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," she added.

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