People with increasing body mass index (BMI) may be at the risk of testing positive for SARS-CoV-2, the virus which causes COVID-19, finds a new study.

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The researchers, from the Chaim Sheba Medical Centre in Israel, found that the odds of testing positive for SARS-CoV-2 were 22 per cent higher in patients who were overweight or obese compared to those with a normal BMI. People with Class I obesity (BMI 30.0-34.9 kg/m²) was linked to a 27 per cent higher risk of testing positive, which increased to 38 per cent for class II obesity (BMI 35.0-39.9 kg/m²), and an 86 per cent higher risk in class III or morbid obesity (BMI at or above 40.0 kg/m²).

Obesity-related factors, including changes to the innate and adaptive immune systems brought on by excess weight, are believed to be associated with an increased risk of contracting various viral diseases. This association between BMI and viral infection risk suggests that a similar relationship may also exist between an individual's BMI and their risk of contracting SARS-CoV-2, said the team led by Hadar Milloh-Raz, from the varsity.

In total 26,030 patients were tested across the study period (between March 16 and December 31, 2020), and 1,178 positive COVID -19 results were recorded. They found every 1 kg/m2 rise in a patient's BMI was associated with an increase of around 2 per cent in the risk of testing positive for SARS-CoV-2. Further, the researchers found that people with diabetes were associated with a 30 per cent higher likelihood of testing positive, while the risk of testing positive was almost six times greater in patients with hypertension.

Conversely, the odds of a positive test were lower among patients with a history of stroke (39 per cent), IHD (55 per cent), and CKD (45 per cent), respectively. However, the study did not explain the reason. The study also did not look at COVID mortality or outcomes, only the risk of testing positive. The findings were presented at the 2021 European Congress on Obesity, held online between May 10 and 13.