COVID-19 Vaccination Doesn’t Lead to Worsening MG, Study Reports

Steve Bryson, PhD avatar

by Steve Bryson, PhD |

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Two doses of the COVID-19 vaccine did not worsen symptoms in 200 people with myasthenia gravis (MG), with mostly injection site-related side-effects reported, matching those seen in the general population, a study reported.

These findings contrast with those of a recent study suggesting that, in very rare cases, COVID-19 vaccines may cause MG symptoms to worsen.

However, because COVID-19 infection is more likely to worsen MG than the vaccination, the authors recommend that MG patients be given the COVID-19 vaccine.

The study, “Retrospective study on the safety of COVID-19 vaccination in myasthenia gravis,” was published in Muscle & Nerve.

In MG, self-reactive antibodies mistakenly attack proteins involved in nerve-muscle communication, causing muscle weakness, including in the muscles that control breathing.

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Infections are the most common cause of disease exacerbations, or flares of symptom worsening. Because vaccines are designed to mimic infections and stimulate an immune response, there are concerns about COVID-19 vaccines possibly triggering exacerbations in people with MG.

A recent study suggested COVID-19 vaccines may cause MG exacerbations in very rare cases.

Researchers at the University Health Network, Canada examined the medical records of people with MG who received two doses of any of the available COVID-19 vaccines and completed assessments by phone. They analyzed data from patients who received two doses of the same vaccine, as well as from those who were given different vaccines.

The team identified 220 MG patients, but excluded two who had congenital MG, five who didn’t get both vaccine doses, and 13 who did not complete phone assessments.

Two patients developed hives and rash after the first dose of Pfizer-BioNTech’s BNT162b2 and were advised not to receive a second vaccine. One developed Bell’s palsy, a temporary episode of facial muscle weakness, after the first vaccine dose and refused a second.

The final analysis included 200 MG patients with a mean age of 64.3 years. More than half (51.5%) were men, and the majority (82%) had generalized MG, a more severe form of the disease wherein weakness is seen across multiple muscle groups.

In this group, 73.5% received the Pfizer-BioNTech vaccine, 12% the Moderna vaccine, and 6% the Oxford-AstraZeneca vaccine. Seventeen participants received mixed vaccines.

The primary outcome, as assessed before the first dose and after each dose, was any changes in MG severity. Assessment tools included the virtual Myasthenia Gravis Impairment Index (vMGII), a measure of disease severity based on 22 patient-reported and six examination items; a single simple question (SSQ) that reflects the patient’s perception of their overall disease status; and patient acceptable symptom state (PASS), a holistic evaluation of the patient’s satisfaction.

All three assessment tools remained stable after the first and second doses of the vaccines compared to before the vaccination, as well as at the last follow-up, the analysis showed.

Almost 90% of participants responded “yes” to the PASS test before and after vaccination, indicating their degree of satisfaction regarding disease burden remained unchanged. The mean value of SSQ remained stable at 82%, and the mean MGII ranged from 7–8 before and after vaccination, “indicating a well-controlled population,” the researchers wrote.

In 11 patients, the SSQ, reflecting their perception of disease status, dropped by 10%, while improving by 10% in nine others after vaccination, “without any clear pattern.” At the last follow-up, 12 participants were worse on the SSQ by 10%, whereas 14 were better. There were no meaningful changes in MGII in those who improved or worsened with the SSQ assessment.

After the first vaccine dose, 60% reported side effects; slightly less (56%) did so after the second vaccine. These mainly included pain at the injection site, as well as fatigue, headache, and fever. No emergency room visits or hospital admissions occurred.

The research team noted these findings may not be generalizable to newly diagnosed MG patients or those who fail to respond to MG-related therapies.

“This study provides evidence that a two-dose regimen of any of the available COVID-19 vaccines is safe without worsening MG status, and with adverse reactions similar to those in the general population,” the team wrote. “We recommend strongly that MG patients receive the COVID-19 vaccine, as COVID-19 infection has a greater likelihood of worsening MG than the vaccination.”