When researchers began to develop what they hoped would be an effective COVID-19 vaccine, they already knew that H1N1 influenza – a novel virus, like COVID-19 – more severely affected patients with overweight or obesity. Patients with a body mass index of 30 or above had a higher risk of hospitalization and death from H1N1.
This is not the first time such a link has been found. A 2017 study from the University of North Carolina at Chapel Hill discovered the flu shot was less effective in patients who had excess weight or obesity. This study included only 1,022 participants, but other small studies show similar results.
