In the U.S., essential drugs like insulin, antibiotics and birth control simply aren’t as effective for over two-thirds of the adult population. As of 2016, 70.1 percent of people over the age of 20 were considered overweight or obese, as measured by having a Body Mass Index of over 25. Though BMI is often identified as a faulty measure of overall health, it can have real implications for the effectiveness of certain medications. Some experts predict that the COVID-19 vaccine could present the same problem.
BMI is calculated using only body weight and height, and therefore reflects little about one’s likelihood for contracting a disease or the development of certain medical conditions. According to Harvard Medical School’s Harvard Health Publishing, “more than half of those considered overweight by BMI had a healthy ‘cardiometabolic profile,’ including a normal blood pressure, cholesterol and blood sugar.”
BMIs also vary heavily along racial, ethnic and economic lines — for example, 85 percent of women of Mexican origin have a BMI of over 25, according to data from the Centers for Disease Control. Of greater concern for vaccinations and specific drugs, however, are people classified as obese, which means having a BMI of over 30. About 40 percent of the general population over 20 meets this criteria in the U.S.
While the label of “obese” can similarly be misconstrued — someone labeled as obese can have a healthy cardiometabolic profile, as well — a BMI within this category is more closely linked to effectiveness issues with medications. Vaccine producers are anticipating that the forthcoming coronavirus vaccine may pose similar issues.
As Chris Xu, CEO of ThermoGenesis, a company that designed rapid COVID antibody tests, explained to Healthline, “Researchers believe that due to increased production of leptin (which correlates with body fat mass) and fat, the obese population has a more difficult time gaining vaccine-induced antibody protection.”
Some medical professionals also speculate that various medications like antibiotics aren’t prescribed in adequate doses for people with higher body weights. With vaccines, experts have thought that inflammation caused by other conditions related to obesity may lessen the effectiveness as well.
It may be a matter of improper injection, too, says Anthony Harris, chief innovation officer and associate medical director for WorkCare. “We know that individuals with a high BMI may have less of an immune response than others,” he explains. “But one of the things that may limit the effectiveness of a vaccine for a high-BMI individual may be whether we inject it in the right tissue. Most flu vaccinations are intramuscular vaccines, so the needle has to go into the right layer of soft tissue and reach muscle. If there’s not careful attention to making sure that needle is in the right layer, that vaccine may not be as effective.”
These issues with drugs and obesity raise the question of why we label them as effective. If an average of 40 to 70 percent of the population may not benefit from a particular drug, it seems inaccurate to broadly classify it as effective overall. Considering that obesity is one health factor presenting an increased risk of severe complications for COVID-19, it seems all the more essential that the forthcoming vaccine properly protect this portion of the population.