Despite rumors, the vaccine against hepatitis B does not increase the risk of multiple sclerosis, a new study shows. On the contrary, according to the researchers, vaccination, especially against the gripe, would be associated with a reduced risk of developing this disease in the years that follow.
Vaccines are regularly the source of controversy. Many critics of the HPV vaccine, for example, have accused it of causing cancer of the cervix, although studies prove instead that it protects. In 1998, a study linked the MMR vaccine (measles, mumps, rubella) with autism. If it has been regularly refuted since, some beliefs die hard. This is particularly the case of the combination of hepatitis B vaccine and the aggravated risk of multiple sclerosis, an inflammatory disease of the central nervous system. Although several studies have already proven that there is no link, new work published in the journal Neurology the 30th of July hit the nail. On the contrary, vaccination, especially against influenza, is associated with a lower risk of multiple sclerosis, say researchers at the University of Munich in Germany.
To arrive at these conclusions, they analyzed 223,000 medical records of the Bavarian health insurance system between 2005 and 2017. Of those monitored, 12,262 were diagnosed with multiple sclerosis or later. By observing which vaccines had been administered and when, scientists were unable to determine that "vaccination is a risk factor for multiple sclerosis," they explain.
Infection Prevention Could Reduce Relapses
On the contrary, vaccination, especially influenza vaccination, was associated with a lower risk of being diagnosed with multiple sclerosis in the next five years, they noted. "Infections are associated with relapses of the disease, the prevention of infections (by vaccination, Ed) could therefore reduce relapses and the risk of multiple sclerosis," they argue.
Another possible hypothesis: "Stimulation of the immune system with vaccine antigens could have a positive effect on the autoimmune response that accompanies the onset and progression of the disease". However this potential "protective effect" has yet to be studied, admit the researchers.
How was this rumor born?
These results are therefore consistent with those of many studies on the subject. "Data that has been in existence for more than fifteen years makes it possible to safely exclude a link between vaccination against hepatitis B virus and the occurrence of multiple sclerosis," notes the government website Vaccination Info Service.
But where did this belief come from, that vaccination against hepatitis B would increase the risk of multiple sclerosis? In the 90s, while the vaccine against hepatitis B was widely administered in France, several people developed multiple sclerosis soon after. Faced with massive media coverage of these cases, the health authorities had to suspend the vaccination campaign in schools, despite the lack of evidence to establish a direct link.
Today in France, multiple sclerosis affects more than 100,000 patients and 5,000 new cases are diagnosed each year. The disease is caused by a disruption of the immune system, which attacks the brain and nerve fibers by destroying myelin sheaths to protect the neurons. Gradually, patients lose the use of their limbs, have problems with vision, motor skills and sensitivity. Multiple sclerosis first manifests itself in a cyclic form before becoming progressive. Unfortunately, at the moment, there is no treatment to cure it. However, remedies are available to slow its evolution and improve the quality of life of patients.