To answer that question, we have to start with how the immune system works. In overweight people, the immune system is often disrupted before they become ill, says Liesbeth van Rossum, internist and hormone specialist at Erasmus MC and professor of obesity and stress hormones. That immune system is needed to attack viruses.
Obesity problem
The problem with obese people is that there is a chronic inflammatory condition in belly fat that keeps the immune system ‘on’ all the time. Incidentally, being overweight is not always a matter of one’s own fault, emphasizes Van Rossum. But it does prevent the immune system from responding well to acute stimuli such as viruses, which can make people more seriously ill from infections, she explains.
Fat contains fat cells and immune cells. “Those fat cells are under stress all the time. As a result, the immune cells have to work to make the fat cells better,” said immunologist Pieter Leenen of Erasmus MC. “As a result, those cells have less time to deal with the coronavirus, for example. to get going.”
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The question is: what does this mean for the effect of vaccinations, in which the production of antibodies in response to a piece of virus in the vaccine is one of the important factors? Van Rossum said in a podcast last year that there is a considerable chance that the vaccine is less effective in obese people, because we see that with some other vaccines.
But there are now some new studies that provide new insights. As a matter of fact, very little research has been done on this. And the studies out there are only about Pfizer and Moderna. Drawing firm conclusions, says Van Rossum, is therefore not possible at the moment.
Effective or not effective?
But obese people do seem to make fewer antibodies after being vaccinated with the corona vaccine. But for the time being, that has no influence on the effectiveness, Van Rossum and Leenen noted in the studies.
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Van Rossum: “For example, in a small-scale Italian study from June 2021 among 248 healthcare employees, you see that the higher the BMI, the fewer antibodies people make.”
Number of antibodies
For example, 147 people with a normal weight were examined. They produced an average concentration of 325 antibodies. For 56 overweight people, the antibody concentration was about 222 and for the 26 obese people, the average was 167.
At the same time, research by Harvard Medical School shows that this has no appreciable influence on protection against infection, explains Van Rossum. “From day seven after the second dose of the Pfizer-BioNTech vaccine, you saw 95.4 percent effectiveness in non-obese people and 94.8 percent effectiveness in obese people. From 14 days after the second dose of the Moderna vaccine, it was 94 percent.” .1 in non-obese people and 91.2 percent for obese people.”
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The fact that fewer antibodies do not always influence the effectiveness has to do with a certain bandwidth, says Van Rossum. “In some cases, more or fewer antibodies are produced than others, and there may still be enough, as shown by the Harvard study.”
It is also important that antibodies do not only determine how well you are protected. “Immune memory also plays an important role. The key question for the future is: does the corona vaccine work just as well in the long term? We know that vaccines for hepatitis B and influenza A work out over time in obese people. Or We don’t know yet that this also applies to Covid-19. Research still needs to be done.”
More research
Further research is now being conducted into the effectiveness of the vaccines in obese people. “In any case, the first results are encouraging.” It remains extremely important for obese people to get vaccinated, she emphasizes. “Because they are more at risk of a serious course of Covid-19.”
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