Comirnaty mRNA Vaccine Safe in MG, Study Concludes
Only 8 of 113 patients who got the COVID-19 vaccine had worsening symptoms after third dose
The Comirnaty mRNA COVID-19 vaccine was safe and well tolerated in people with myasthenia gravis (MG), a study confirmed.
Worsening of MG symptoms after the third vaccine dose occurred in eight of the 113 study participants (7.1%) who were all successfully treated with standard immunoglobulins (IVIG).
While data suggested symptom worsening occurred in those treated with anti-inflammatory corticosteroids who were younger at the onset of MG, had thymus gland disease, or were positive for anti-MuSK antibodies, the findings were not considered statically significant.
“To our knowledge, our study is the only one performed on more than 100 patients who received the complete vaccinal cycle and whose features were similar to the global MG population,” the researchers wrote. “Because of that, our results can better confirm the safety of the vaccine in MG.”
The study, “COVID19 vaccine in myasthenia gravis patients: safety and possible predictors of disease exacerbation,” was published in Neurological Sciences.
In MG, an altered immune response impairs communication between nerves and muscles, causing muscle weakness. Episodes of symptom worsening, called exacerbations, include myasthenic crises, when the muscles that support breathing weaken significantly, often resulting in hospitalization.
Vaccines are designed to mimic infection and stimulate an anti-microbial immune response without causing an infection-related disease.
The Pfizer/BioNTech mRNA vaccine, sold as Comirnaty, was developed to prevent or reduce the impact of SARS-Cov-2 infection — the virus that causes COVID-19. The vaccine delivers instructions to make the SARS-Cov-2 spike protein to cells in the form of messenger RNA (mRNA) — the template molecule that carries information to make proteins.
People with autoimmune conditions, such as MG, were excluded from clinical trials because it was unclear whether an immune response to the vaccine might also trigger autoimmune exacerbations. Comirnaty was found to be safe and effective in people who didn’t have MG, but its potential to worsen MG symptoms needed to be determined.
Effect of Comirnaty vaccine on MG patients
Researchers in Italy reviewed the medical records of 113 MG patients (46.9% women) who received three doses of the Comirnaty vaccine. Disease status was evaluated using MG Status and Treatment Intensity (MGSTI) scores, with higher scores indicating worse disease.
After the second dose, the most commonly reported side effects were flu-like syndrome, headache, and a red rash at the site of the injections, which were all resolved in a few days. All the participants were asked to complete the MGSTI during their last visit before the third dose and after vaccination if an exacerbation occurred.
Among the 113 MG patients evaluated, eight (7.1%) had worsening symptoms after the third dose.
Four had an MGSTI of 1 or 2 (low disease activity) and were being treated with anti-inflammatory corticosteroids before receiving the vaccine. Symptom worsening began between three days and two weeks after being vaccinated.
Three had an MGSTI of 3, 4, and 5 and were treated with corticosteroids and other immune-suppressive therapies before the vaccine, with exacerbations occurring after two weeks. One participant who was not being treated and had an MGSTI of 0, worsened seven days after being vaccinated.
All those who had an exacerbation reached an MGSTI of 6 and were successfully treated with IVIG, a treatment wherein immune proteins from donors are given to patients to neutralize disease-causing autoantibodies in the bloodstream. Further tests confirmed IVIG therapy didn’t impact the levels of anti-SARS-Cov-2 antibodies elicited by the vaccine.
Although there was a higher prevalence of exacerbation after vaccination in patients treated with corticosteroids, this increase wasn’t considered statistically significant.
The researchers found similar non-significant relationships between exacerbations after vaccination and younger age of MG onset, thymus gland disease, and the presence of autoantibodies that target muscle-specific kinase (MuSK), a protein that plays a role in nerve-muscle communication.
“Our study suggests that COVID19 vaccine can be considered safe in patients affected by MG,” the researchers wrote. “Treatment with [corticosteriods], the young age, the presence of anti-MuSK, and the thymic pathology [disease] were common features in those who experienced the exacerbation of symptoms. For this reason, further studies should be performed in order to assess their impact on the response to the vaccine.”
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