Governments and the pharmaceutical industry are currently relying on vaccines to tackle the coronavirus pandemic. Around 190 vaccines are being tested or prepared. But there is a small problem: Existing diseases can severely affect the immune system and thus the effectiveness of the vaccination.
In the United States, where over 40 million people have probably already been infected and nearly 155,000 have died, the effectiveness of this vaccine is hampered by another epidemic that preceded Covid-19: obesity.
Scientists know that vaccines developed to protect against influenza, hepatitis B, tetanus, and rabies can be less effective in obese adults than in normal-weight people, making them more susceptible to infection and disease. There is little reason to believe that Covid-19 vaccines will be different, obesity researchers say.
“Will it still work for overweight people? Our prediction is no.”
says Raz Shaikh, an associate professor of nutrition at the University of North Carolina-Chapel Hil according to Kaiser Health News.
More than 107 million American adults are obese. On the one hand, this causes a far higher chance of getting sick in the event of infection, and that with even more severe courses. For the same reason, the coronavirus vaccine gives them poor immunity. Addiposity weakens the immune system and thus the effectiveness of vaccines.
How we reportedAlready in March, at the beginning of the global pandemic, a study from China, which received little attention from the mainstream media, revealed that overweight patients with Covid-19 died more frequently than leaner ones. Now the United States, whose population is one of the most serious, is also coming to the conclusion that this is one of the causes of serious illness and deaths and that the effectiveness of vaccines is therefore not guaranteed.
When intensive care units in New York, New Jersey, and elsewhere were filled with patients, the Federal Centers for Disease Control and Prevention warned that overweight people with a Body Mass Index (BMI) of 40 or more – known as pathological obesity – were among the groups The highest risk of becoming seriously ill with Covid-19. About 9% of American adults belong to this extreme category.
High BMI risk factor
As weeks passed and a clearer picture of who was hospitalized came into focus, the federal health authorities expanded their warning to include individuals with a BMI of 30 or more. This significantly expanded the number of those who are considered susceptible to the most serious cases of infection to 42.4% of American adults.
And in Europe, too, the proportion is not exactly small, but different per country, as can be seen from the table below. Young people are also badly affected. In Greece and Italy there are almost three times as many overweight or obese children as in Sweden or Switzerland. While the number of overweight children in Central and Western Europe is stagnating, according to a study in JAMA Pediatrics (2019; doi: 10.1001 / jamapediatrics.2019.2430) there has been an increase in many Mediterranean countries, for which the researchers are partly responsible for the economic crisis after 2007 do.
Anyone who travels to Mediterranean countries in summer will notice the high proportion of overweight and obese children. The studies confirm this impression. In Greece and Italy, every third child aged 7 to 13 is overweight (36.8 and 35.2%). In Sweden and Switzerland it is only every sixth child of the same age (15.0 and 17.4%). In Germany too, the proportion is below the European average at 18.9%.
Obesity affects the immune response
It has long been known that obesity is a significant risk factor for death from cardiovascular disease and cancer. However, scientists in the emerging field of immune metabolism have found that obesity also affects the body’s immune response and increases the risk of infection by pathogens such as influenza and the coronavirus.
With influenza, obesity has emerged as a factor that makes it more difficult to vaccinate adults against infections. The question is whether this applies to Covid-19.
A healthy immune system turns inflammation on and off, calls for white blood cells, and sends out proteins to fight infections. Vaccines use this inflammatory response. To produce antibodies and especially the long-lived T cells. However, blood tests show that overweight people and people with related metabolic risk factors such as high blood pressure and elevated blood sugar levels have a condition of chronic mild inflammation. The inflammation turns on and stays on.
Fat tissue – or fat – in the abdomen, liver and other organs is not inactive. It contains specialized cells that send out molecules, such as the hormone leptin, which scientists suspect it triggers this chronic inflammatory condition. While the exact biological mechanisms are still under investigation, chronic inflammation appears to affect the immune response to vaccines and potentially expose obese people to preventable diseases even after vaccination.
Being overweight reduces immunity through vaccinations
Evidence that overweight people react weakly to common vaccines was first provided in 1985 when overweight hospital staff receiving the hepatitis B vaccine showed a significant decrease in protection 11 months later that was not seen in non-overweight workers. The finding was repeated in a follow-up study using longer needles to ensure that the vaccine was injected into muscle rather than fat.
In 2017, scientists from the University of North Carolina at Chapel Hill made a critical statement about the limitations of the influenza vaccine. In one in the International Journal of Obesity published articles researchers showed for the first time that vaccinated obese adults suffer from influenza or flu-like illnesses twice as often as adults with healthy weight.
Unsurprisingly, the study found that adults with obesity produced a protective level of antibodies to the influenza vaccine, but these adults still responded poorly. One thesis is that the T cells do not react as they do in people who are not overweight. We have seen that even with SARS and corona viruses, the T cells achieve the more important and long-lasting immunity than antibodies against infection.
Based on these findings, it seems that vaccination is of the least help to those at risk. Those who already have a strong immune system and therefore count to 85 to 90 percent of people who do not even notice the infection should therefore undergo vaccinations that have side effects.