ABSTRACT
Introduction: Most children who contract SARS-CoV-2 infection are asymptomatic or mildly symptomatic. However, a subset go on to develop a potentially life-threatening hyperinflammatory condition called multisystem inflammatory syndrome in children (MIS-C) 4-6 weeks after COVID-19. The mechanisms by which MIS-C occurs are not yet clear, resulting in hesitation to vaccinate this subset of children against SARS-CoV-2 due to concerns for a reoccurrence of hyperinflammation. Objectives: To evaluate outcomes following SARS-CoV-2 vaccination in patients who were previously diagnosed with MIS-C after COVID-19. Methods: Medical records of patients who were treated for MIS-C at our institution were retrospectively reviewed. Details for those who were subsequently vaccinated against SARS-CoV-2 were extracted. Results: A total of 164 patients were treated for MIS-C between May 2020 and May 2021. 22 patients were 16 years of age or older and an additional 30 patients were age 12-15 years, resulting in a total of 52 patients eligible for SARS-CoV-2 vaccination. 10 (19%) of these patients were vaccinated using the Pfizer-BioNTech product in our COVID-19 vaccine clinic. The age of the patients ranged from 12 to 17 years. 8 were male, and 8 were from racial/ethnic minority groups. All were generally healthy (3 asthma, 1 repaired congenital heart disease) prior to their MIS-C diagnosis. The patients presented between July 2020 and February 2021 with a febrile illness, and fulfilled the case definition for MIS-C established by the Centers for Disease Control and Prevention, including all 10 having positive SARS-CoV-2 serologic testing and 9 with myocarditis or coronary changes (measured by troponin elevation and/or electrocardiographic or echocardiographic evidence). 8 presented in shock or with hypotension, and 6 were admitted to the intensive care unit (ICU), among which 3 required vasoactive medications and 2 intubation. ICU length of stay ranged from 2-15 days, and total hospital stay from 2-23 days. All 10 patients were treated with corticosteroids, 8 received intravenous immunoglobulin, and 5 anakinra. All patients had normal cardiac function without coronary artery dilation at the time of last cardiology follow-up. The patients were vaccinated an average of 199 days from MIS-C hospitalization discharge (range 83 to 337 days). Thus far, a median of 57 days (range 1 to 117 days) has elapsed since 9 of the 10 patients completed the second vaccine dose. None has developed a recurrence of MIS-C or a hyperinflammatory condition. No significant adverse events have occurred following vaccination. Conclusion: These 10 patients who experienced MIS-C after COVID-19 have tolerated vaccination against SARS-CoV-2 without the subsequent development of a similar hyperinflammatory state providing critical information as the COVID-19 pandemic continues to rage across the globe. As we move toward vaccination for children younger than 12 years, a growing number of prior MIS-C patients (average age 8-9 years) will become eligible for vaccination. Given the risk of re-infection with SARS-CoV-2 and the known additive protection from re-infection provided by vaccinating previously infected individuals, it is imperative that patients with a history of MIS-C be offered vaccination against SARS-CoV-2.