A 62-year-old man in Germany decided to take the Covid-19 vaccine 217 times in 29 months for “private reasons”. But, somewhat surprisingly, he does not appear to have suffered any ill effects from over-immunization, according to a newly published case study in 2017. The Lancet Infectious Diseases.
Of course, this case is just one person, so the findings cannot be extrapolated to the general population. But they conflict with widely held concerns among researchers that overvaccination may lead to a weakened immune response. Some experts have raised this concern when discussing how often people should get Covid-19 booster doses.
With long-term exposure to disease-causing bacteria, “there are signs that certain types of immune cells, called T cells, become fatigued, causing them to release fewer pro-inflammatory messenger substances,” said Kilian, the study’s lead author. Schober comes from the Institute of Microbiology – Clinical Microbiology, Immunology and Hygiene. This, along with other effects, may lead to “immune tolerance,” leading to a weaker response that is less effective against pathogens, Schaub explained in a press release.
The German man’s extreme history of overvaccination seems to be a good example of looking for evidence of such tolerance and weaker responses. Schaub and his colleagues learned about the man’s case through headlines — officials had launched a fraud investigation into the man, confirming 130 vaccinations over nine months, but no criminal charges were ever filed. “We then contacted him and invited him to Erlangen to undergo various tests [a city in Bavaria]”, Schober said. “He was very interested in it. “The man subsequently reported a further 87 vaccinations to the researchers, which included a total of eight different vaccine formulations, including newer boosters.
Researchers collected blood and saliva samples from the man between doses 214 and 217 of the vaccine. They compared his immune response to that of 29 people who received the standard three-dose series.
During his dizzying course of vaccinations, the man never reported any vaccine side effects, and his clinical tests found no abnormalities associated with over-vaccination. The researchers looked at his response to the vaccine in detail and found that while some aspects of his protection were greater, overall his immune response was functionally similar to that of someone who had received a much smaller dose. After receiving the new dose, vaccine-stimulated antibody levels in his blood rose, but then began to fall, similar to those in the control group.
His antibodies appeared to be 5 to 11 times more capable of neutralizing SARS-CoV-2 than the control group, but the researchers noted that this was due to higher numbers of antibodies rather than more effective antibodies. Levels of specific immune cell subsets, namely B cells and T effector cells trained against the SARS-CoV-2 spike protein, were increased compared with controls. But they seem to be working fine. As another control, the researchers also looked at the man’s immune response to an unrelated Epstein-Barr virus, which causes mononucleosis. They found that uncontrolled immunization did not negatively affect the response to the virus, suggesting that there was no adverse effect on the immune response overall.
In the end, multiple tests showed the man had never been infected with SARS-CoV-2. But the researchers cautioned that this may be due to other precautions the man took in addition to receiving the 217 vaccine.
“Together, our case report demonstrates that SARS-CoV-2 overvaccination does not lead to adverse events and increases the number of spike-specific antibodies and T cells without having a strong impact on the intrinsic quality of the adaptive immune response. Positive or negative effects,” the authors concluded. “Importantly,” they added, “we do not endorse overvaccination as a strategy to enhance adaptive immunity.”
This story originally appeared in Technology Arts Festival.