Studies have shown that flu, hepatitis B, tetanus and rabies vaccines can be less effective in obese adults than in the general population, and there’s no reason to believe a coronavirus vaccine will be any different.
The CDC initially warned that people who were morbidly obese —having a BMI of 40 or more or were about 100 pounds overweight — were among the groups at highest risk of becoming severely ill with COVID-19.
It wasn’t long before that warning was expanded to include people with a body mass index of 30 or more.
How does obesity prevent vaccines from working correctly?
According to Varney: “A healthy immune system turns inflammation on and off as needed, calling on white blood cells and sending out proteins to fight infection. Vaccines harness that inflammatory response. But blood tests show that obese people and people with related metabolic risk factors such as high blood pressure and elevated blood sugar levels experience a state of chronic mild inflammation; the inflammation turns on and stays on.”
Although scientists are still researching its causes, it seems chronic inflammation interferes with the body’s immune response to vaccines.
“Obesity is a serious global problem, and the suboptimal vaccine-induced immune responses observed in the obese population cannot be ignored,” researchers from the Mayo Clinic’s Vaccine Research Group wrote in a 2015 study published in the journal Vaccine.