[I]n the United States, where at least 4.6 million people have been infected and nearly 155,000 have died, the promise of [a coronavirus] vaccine is hampered by a vexing epidemic that long preceded Covid-19: obesity.
Scientists know that vaccines engineered to protect the public from influenza, hepatitis B, tetanus and rabies can be less effective in obese adults than in the general population, leaving them more vulnerable to infection and illness. There is little reason to believe, obesity researchers say, that Covid-19 vaccines will be any different.
“Will we have a Covid vaccine next year tailored to the obese? No way,” said Raz Shaikh, an associate professor of nutrition at the University of North Carolina-Chapel Hill.
“Will it still work in the obese? Our prediction is no.”
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… While the exact biological mechanisms are still being investigated, chronic inflammation seems to interfere with the immune response to vaccines, possibly subjecting obese people to preventable illnesses even after vaccination.