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This One Thing May Make the COVID Vaccine Less Effective, Experts Say

Scientists say that people whose immune system is adversely affected by obesity may ultimately lack vaccine-induced immunity.
FACT CHECKED BY Alek Korab

Pfizer's COVID-19 vaccine sailed through Food and Drug Administration (FDA) emergency approvals last week, which paved the way for those most at risk of the coronavirus—chiefly, nursing home residents and healthcare workers—to potentially start getting vaccinated as soon as this week. At the earliest, officials say, the general public can expect distribution of the vaccine by the spring. Now begins the great vaccination rollout, an historic effort that begins with nearly 3 million vaccines shipping out to locations in every U.S. state in real time.

As the vaccines spread far and wide, it's worth noting that there will be some mild side effects. As Dr. Fauci has stated, many who get vaccinated can expect to get a fever. Other side effects include chills, headaches, nausea, fatigue, and some pain, "local swelling, and irritation," former FDA Chief Dr. Margaret Hamburg told CNBC's Squawk Box last week. As many outlets reported, two individuals in the United Kingdom suffered an allergic reaction—though medical experts have been quick to note that such instances are rare.

But there's one condition that many health experts are saying could potentially make the vaccine less effective: Obesity.

Countless studies have shown that those suffering from obesity are among the most affected by severe complications related to COVID-19, including death. But experts are now saying that obesity may also impact how effective the COVID-19 vaccine is. "Obesity affects many facets of our immune system and results in dysregulated immune responses," explains Rajat Madan, MD, an infectious diseases specialist and assistant professor in the Department of Internal Medicine at the UC College of Medicine at UC Health. "Therefore, the effects of vaccination in an obese person can be very different, compared to a non-obese person."

In the past, vaccines created to protect us from the flu, hepatitis B, rabies, tetanus, have all been scientifically proven to be less effective in obese people than those who are not obese. Many scientists simply believe that the COVID vaccine will perform in a similar manner—and the reason has more to do with the nature of vaccines than with COVID itself.

Shenggen Fan, Chair Professor and Dean of Academy of Global Food Economics and Policy at China Agricultural University, recently wrote in the UK's The Telegraph: "Studies have shown that those people whose immune system is adversely affected by obesity may ultimately lack vaccine-induced immunity."

As the Kaiser Family Foundation explains it, "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."

In other words, the vaccine may not fully work in obese patients as it's intended.

Of course, that doesn't mean that obese people shouldn't get vaccinated. Quite the opposite. However, if you have the power and the determination to adopt healthier habits, now would be a wise time to do so. As Fan notes, leading a sedentary lifestyle and eating "ultra-processed foods with high sugar and fats" is known to drive obesity. Not everyone will be able to do so, of course. As Fan notes, 70 percent of individuals who are overweight or obese come from low- and middle-income countries.

If you're interested in changing your own eating habits for the better, please know that here are some of the most unhealthy foods you should cut out of your diet starting now. By becoming more active and eating more healthy and nutritious wholes foods, you can start to counteract those harmful habits today. The benefits of eating healthier not only include weight loss, but also clearer skin, more energy, shinier hair, a better mood, better sleep, less cravings, better hormonal balance, a stronger immune system, better blood sugar, and improved brain health. And now, that list may even include the benefit of having the COVID vaccine work better for you. And for some great weight loss advice you can use, don't miss this list of The 12 Foods That Drive the Most Weight Loss of All, Say Experts.

William Mayle
William Mayle is a UK-based writer who specializes in science, health, fitness, and other lifestyle topics. Read more