The Impacts of Influenza Infection and Vaccination on Exacerbation of Myasthenia Gravis

Abstract

Background and PurposeUpper respiratory infection (URI), including influenza, may exacerbate the symptoms of myasthenia gravis (MG), which is an autoimmune disease that causes muscle weakness. There is also concern that the influenza vaccine may trigger or worsen autoimmune diseases. The objective of this study was to determine the impacts of influenza infection and vaccination on symptom severity in MG patients.MethodsPatients diagnosed with MG were enrolled from 10 university-affiliated hospitals between March and August 2015. Subjects completed a questionnaire at the first routine follow-up visit after enrolling in the study. The patient history was obtained to determine whether a URI had been experienced during the previous winter, if an influenza vaccination had been administered before the previous winter, and whether their MG symptoms were exacerbated during or following either a URI or vaccination. Influenza-like illness (ILI) was defined and differentiated from the common cold as a fever of ≥38℃ accompanied by a cough and/or a sore throat.ResultsOf the 258 enrolled patients [aged 54.1±15.2 years (mean±SD), 112 men, and 185 with generalized MG], 133 (51.6%) had received an influenza vaccination and 121 (46.9%) had experienced a common cold (96 patients) or ILI (25 patients) during the analysis period. MG symptoms were aggravated in 10 (40%) patients after ILI, whereas only 2 (1.5%) experienced aggravation following influenza vaccination. The rate of symptom aggravation was significantly higher in patients experiencing an ILI (10/25, 40%) than in those with the common cold (15/96, 15.6%, p=0.006).ConclusionsThe results of this study suggest that the potential risk of aggravating autoimmune disease is higher for ILI than for influenza vaccination, which further suggests that influenza vaccination can be offered to patients with MG.

Factors associated with acute exacerbations of myasthenia gravis

“…The patient population in this study experienced no adverse effects or exacerbations as a result of vaccines, which is consistent with previous studies on the influenza vaccine . Other studies have shown that an influenza like illness is associated with MG exacerbations leading to higher rates of MG symptom aggravation than the influenza vaccination . In our study, many patients with MG were on immunosuppressive medications at the time of a VPI that preceded an exacerbation.…”

“…6,29 Other studies have shown that an influenza like illness is associated with MG exacerbations leading to higher rates of MG symptom aggravation than the influenza vaccination. 7 In our study, many patients with MG were on immunosuppressive medications at the time of a VPI that preceded an exacerbation. These patients did Further studies are needed to establish vaccination guidelines in MG patients.…”

“…Prior studies highlighted the importance of immunizations by demonstrating the benefits of influenza vaccination in MG patients . Influenza‐like illnesses and pneumonia lead to worsened MG exacerbations . Among the contributors to MG exacerbations, infections account for 40‐70% of cases and a 3‐8% mortality rate .…”

“…6 Influenza-like illnesses and pneumonia lead to worsened MG exacerbations. 7 Among the contributors to MG exacerbations, infections account for 40-70% of cases and a 3-8% mortality rate. 8,9 The Centers for Disease Control and Prevention broadly recommends annual influenza vaccinations for all persons over the age of 6 months and notes the particular importance in persons at increased risk for severe complications including those immunosuppressed by medications.…”

Serious infections in patients with myasthenia gravis: population‐based cohort study

“…Influenza was relatively more common in MG, although our numbers were small, as we only captured patients requiring emergency department or inpatient care. Although theoretical risks of MG disease flare-up exist with annual influenza vaccination, two studies (including one in Ontario) did not find an increased risk of MG exacerbation after influenza vaccination [18,19] and most guidelines recommend in favor of influenza vaccination in patients with MG, particularly those patients with co-existent cardiac or respiratory illnesses [7,20].…”