The results are overwhelming. A large study carried out by researchers at the Technical University of Munich (Germany) and published in the journalNeurology has concluded thatvaccines are not a risk factor for multiple sclerosis(EM). Instead, the findings reveal a consistent link between high vaccination rates and a lower chance of developing this condition.
The expertsstudied data from more than 200,000 peoplerepresentative of the general population. The data comes from the records of the Bavarian Association of Statutory Health Insurance Physicians covering the period 2005-2017.
The records contained the patients’ vaccination history and diagnosed medical conditions and includeddata on 12,262 people diagnosed with multiple sclerosis.The data set included vaccination dates for chickenpox, measles, mumps, rubella, influenza, meningococci, pneumococci, human papillomavirus, tick-borne encephalitis, and hepatitis A and B.
The researchers used statistical tools to assess any link between multiple sclerosis and vaccines in the five years prior to diagnosis.
The results “did not reveal that vaccination is a risk factor for multiple sclerosis,”the authors concluded in their article.
An unpredictable autoimmune disease
Multiple sclerosis is a long-term disease that damages the central nervous system by destroying the insulation around nerve fibers. Experts believe that this disease is an autoimmune condition in which the immune system attacks the central nervous system in the same way that it defends against threats, such as viruses and bacteria.
According to the National Multiple Sclerosis Society, MS affects more than 2.3 million people worldwide. Although it can appear at any age, it usually develops between the ages of 20 and 50. And women are three times more likely to develop multiple sclerosis than men.
The symptoms of multiple sclerosis are unpredictable and vary from person to person, depending on where the damage to the central nervous system occurs. There may be a pattern of flare-ups that come and go, or symptoms may get worse over time.
People with multiple sclerosis often experience fatigue, numbness, impaired vision, balance and coordination problems, and speech difficulties. They may also experience problems with memory and concentration. Occasionally, it can cause blindness and paralysis.
For all vaccines
The study’s lead author, Bernhard Hemmer, head of the Department of Neurology at the Klinikum rechts der Isar hospital at the Technical University of Munich, and his colleagues set out to test the hypothesis that vaccination is a risk factor for this disease. They analyzed the data in various ways, using “different time frames, control cohorts, and multiple sclerosis cohort definitions.”
Examining different control cohorts, they compared individuals with multiple sclerosis to those without. They also compared multiple sclerosis patients with individuals suffering from two other autoimmune diseases: Crohn’s disease and psoriasis.
The results revealed that in the 5 years before receiving a diagnosis, participants who developed multiple sclerosis had received fewer vaccinations than those who did not develop the condition.
“The odds of MS were lower in participants with a registered vaccine,” the authors write.
The finding was confirmed in all the vaccines they investigated, and “most pronounced for vaccines against influenza and tick-borne encephalitis.”
Possible immune system reasons
The researchers suggest that one reason for this discovery could be that people who develop MS notice their symptoms long before they are diagnosed and may avoid vaccines to avoid stressing their immune systems.
“Such effects are, in fact, evident in our data,” says study lead author Alexander Hapfelmeier, from the Institute for Medical Informatics, Statistics and Epidemiology at the Technical University of Munich.
Another possible reason behind the findings is that the vaccines somehow prevent the immune system from making an attack on the central nervous system. The authors call for more studies to investigate this effect.
“In any case, given the large volume of data analyzed, we can state conclusively that there is no evidence that recent vaccination increases the likelihood of MS or the onset of an initial episode of MS,” concludes Alexander Hapfelmeie.
Referencia: A large case-control study on vaccination as risk factor for multiple sclerosis Alexander Hapfelmeier, Christiane Gasperi, Ewan Donnachie, Bernhard Hemmer. Neurology 2019. DOI: https://doi.org/10.1212/WNL.0000000000008012
