Vaccination does not trigger autoimmunity linked to myasthenia gravis in pediatric patients, a study based on records of the U.S. Department of Health and Human Services suggests.
The findings of the study “Pediatric Myasthenia Gravis After Vaccination in the United States. A Report from the CDC/FDA Vaccine Adverse Event Reporting System. (1990–2017)” will be presented at the 2018 Annual Meeting of the American Academy of Neurology (AAN) in Los Angeles, California, April 21-27. The presentation is part of a session titled Child Neurology and Developmental Neurology: Neuromuscular Disease.
Myasthenia gravis is characterized by increased production of antibodies that prevent the normal communication between nerve and muscle cells. This leads to muscle weakness and impaired responsiveness. Although is still unclear what causes this disease, thymus overgrowth and infections have been suggested as contributors for a hyperactive immune system and high antibody burden.
Vaccines are given to children in infancy to prevent serious, life-threatening infections. They teach the immune system to recognize what is foreign and possibly dangerous, so the next time immune cells encounter those threats they can respond and ward off the disease.
Although vaccines are very important, little is known about their impact on the development of autoimmune diseases such as myasthenia gravis.
A team of Rutgers University researchers revised data collected between 1990-2017 from the Vaccine Adverse Event Reporting System (VAERS), sponsored by the U.S. Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC). They focused on the incidence and characteristics of myasthenia gravis in children after vaccination.
They found records of 33 cases of myasthenia gravis, eight boys and 24 girls aged between 2.4 months and 18 years. About 94% of cases were new diagnosis after vaccination. Twenty cases were reported as definite diagnosis, and 13 as possible myasthenia gravis.
For 22.5% of newly diagnosed patients the presenting symptom of the disease was myasthenia crisis, whereas 35.4% had ocular symptoms and 39.3% had generalized symptoms.
The incidence of pediatric myasthenia gravis after vaccination was found to be 1.2 cases per year, which is within the range reported for the general population. This finding suggests that vaccination does not increase the risk of developing the disease.
Still, the researchers found that in 45% of cases the onset of myasthenia gravis happened within the first six weeks after vaccination, 9% between six and 12 weeks, and 42.4 % after 12 weeks. About 45.5% of cases occurred after HPV vaccine and 27.3% of hepatitis vaccine.
“The unbalanced distribution of pediatric myasthenia gravis cases in the first 6 weeks after vaccination suggests that some cases could be triggered by vaccination,” the researchers wrote.
Additional studies and continuous monitoring of pediatric myasthenia gravis onset after vaccination are warranted to further evaluate this potential association.