Vaccinated Patients With MG Fare Better With COVID-19, Study Finds

A new study based on a small cohort of people with myasthenia gravis (MG) suggests vaccination against SARS-CoV-2 can meaningfully reduce the risk of hospitalization and death.

The new findings are part of an emerging body of evidence looking at how people with MG are affected by COVID-19. This study was published in Life (Basel).

The study investigators said particular features of MG—such as bulbar and respiratory muscle weakness—could make someone with the disease more vulnerable to COVID-19. Viral diseases like MG can lead to worsening MG symptoms, they said, and some of the drugs used to treat COVID-19 have been linked with increased muscle weakness in people with MG.

To gain a better understanding of COVID-19 outcomes in people with MG, and in particular, whether vaccination affected those outcomes, the investigators retrospectively analyzed 27 cases of people in northwest Italy who had MG and got COVID-19. Thirteen of those patients got the disease before being vaccinated. The other 14 were vaccinated at the time of their positive test results.

The 2 cohorts had similar levels of disease severity to start. Their average score on the Myasthenia Gravis Foundation of American scale was class III prior to infection with SARS-CoV-2. The unvaccinated cohort was slightly older, with an average age of 68 years vs 63 years in the vaccinated group. However, both groups had an average MG duration of 7 years.

This analysis showed clear differences in outcomes between the 2 groups. Eight of the 13 unvaccinated patients had severe COVID-19 and required hospitalization, while just 1 of the 14 vaccinated patients did. That single vaccinated patient who was hospitalized was also the only vaccinated patient who died; 4 of the 13 unvaccinated patients died.

When investigators looked at factors associated with worse COVID-19 outcomes, they found that unvaccinated patients who died from the infection were more likely to have a history of more severe MG symptoms, although their symptoms were not significantly worse at the time of their SARS-CoV-2 infection. Patients who were older at MG onset and at SARS-CoV-2 infection also had more severe cases of COVID-19, but only if they were unvaccinated.

The investigators noted that some have worried about how well patients who were treated with anti-CD20 monoclonal antibodies would respond to vaccination. Previous studies into the question have yielded mixed results, the authors said, but one meta-analysis showed people taking anti-CD20 medications had a significantly reduced humoral response to COVID-19 vaccination. Indeed, the single vaccinated patient who died had been taking the anti-CD20 agent, rituximab (Rituxan).

Still, the authors said the overall data show vaccination is still beneficial for most people with MG, and thus they said vaccination should be seen as providing a protective role.

“Despite the reduction in humoral responses, some studies have shown that stronger SARS-CoV-2–specific T-cell responses determine a less severe infection, and in patients treated with anti-CD20 therapy, robust T-cell responses to SARS-CoV-2 vaccination have been reported,” they said. “[T]herefore, vaccination may confer protection even in the absence of an identifiable humoral response.”

The investigators noted that in Italy and elsewhere, people with MG have been prioritized for access to vaccination. The findings of the new study support such policy decisions, they said.

Reference

Scarsi E, Massucco S, Ferraro PM, et al. Comparing the impact of COVID-19 on vaccinated and unvaccinated patients affected by myasthenia gravis. Life (Basel). Published online April 21, 2023. doi:10.3390/life13041064