Patients With MS Less Likely to Have Received Vaccinations Before MS Diagnosis

In the 5 years before being diagnosed, patients with multiple sclerosis (MS) were less likely to receive vaccinations than comparator groups, according to a new study from the Technical University of Munich and published in Neurology.

The researchers were investigating the hypothesis that vaccination is a risk factor for developing MS, but instead found that vaccination may be associated with a lower likelihood of being diagnosed with MS in the next 5 years.

The causes for this connection, according to lead author Alexander Hapfelmeier, PhD, remain a mystery.

“It may be that people perceive the disease long before they are diagnosed and therefore avoid putting additional stress on their immune system,” he said in a statement. “Such effects are in fact evident in our data. Or perhaps the vaccines have a protective effect that prevents the immune system from attacking the nervous system. In any case, given the large volume of data analyzed, we can conclusively state that there is no evidence that recent vaccination increases the likelihood of MS or the onset of an initial MS episode.”

The researchers analyzed ambulatory claims data from 2005 to 2017 from the Bavarian Association of Statutory Health Insurance Physicians. They assessed the relation between MS among 12,262 patients and vaccinations in the 5 years before they were diagnosed. Patients newly diagnosed with Crohn disease (n — 19,296) and psoriasis (n = 112,292), as well as patients with no autoimmune disease (n = 79,185) were the control subjects.

Patients with a recorded vaccination had lower odds of MS (odds ratio [OR] 0.870, P <.001 vs participants without autoimmune disease; OR 0.919, P <.001 vs participants with Crohn disease; OR 0.973, P = .177 vs participants with psoriasis). The researchers investigated vaccines for pneumococci, meningococci, mumps, measles, rubella, chickenpox, human papillomavirus, hepatitis A and B, tick-borne encephalitis (TBE) and influenza. The potentially protective effect was more pronounced for vaccinations against influenza and TBE, the authors noted.

The fact that patients with Crohn disease and psoriasis had as many vaccinations as the healthy control group ruled out the possibility that the results were an underlying effect of chronic diseases in general.

"We already know from other studies that MS sufferers show atypical behavior and medical history long before they are diagnosed,” said Bernhard Hemmer, PhD. “For example, they are more prone to mental illnesses and also tend to have fewer children. All this clearly indicates that MS is perceived long before any neurological symptoms appear. We therefore need to find suitable markers to diagnose the condition earlier. We see this as one of our most important tasks."

Reference

Hapfelmeier A, Gasperi C, Donnachie E, Hemmer B. A large case-control study on vaccination as risk factor for multiple sclerosis [published online July 30, 2019]. Neurology. doi: 10.1212/WNL.0000000000008012.