DISCUSSION
Our patient exhibited no severe symptoms and fully recovered from COVID-19 despite his immunosuppressed status. The clinical course of COVID-19 was reportedly less severe in the pediatric population than adults.1 His young age was possibly a contributing factor for the mild clinical course. Other known risk factors for severe COVID-19 include underlying diseases such as hypertension, diabetes, obesity, and lung diseases. However, the relationship between immunocompromised states due to the underlying disease or immunosuppressive treatment and COVID-19 severity remains controversial. Some studies reported that immunocompromised patients had favorable outcomes compared to the general population.10,11Hyperactivation of immune response and excessive inflammatory reaction were associated with the pathogenesis of severe COVID-19.12 Among the previously reported nine cases of COVID-19 in patients with AA, there was one patient who developed COVID-19 during cyclosporine treatment and the patient fully recovered.3 Therefore, immunosuppression from AA and IST, including continued cyclosporine use, possibly contributed to the uncomplicated course in our patient, despite an increased risk of viral invasion and delayed viral elimination.
To evaluate the immune response to SARS-CoV-2 in this patient, a serological assay was conducted. The anti-S1 and anti-RBD IgA levels significantly increased before the changes in IgG and IgM levels. This observation was consistent with the findings of a previous study, which conducted a serological assay in a non-AA cohort.13Since spike proteins are integral to viral entry into cells,14,15 IgA might play an important role for effective control of the infection. The anti-S1 and anti-N IgG levels subsequently increased, but they peaked at levels below the cutoff values. The anti-RBD-specific IgG level was almost unchanged in our patient. These differed from what was observed in other patients with COVID-19 (mostly immunocompetent) in the University of Tokyo Hospital, whose anti-SARS-CoV-2 IgG level increased significantly in all cases.16 In addition, in a previous case series on COVID-19 with AA, all four patients (with one on IST) had an elevated anti-spike protein IgG level after COVID-19.3 However, the effect of AA and IST on decreased IgG production and a favorable outcome warrants additional investigation.
In summary, we reported a case of COVID-19 in a patient with AA undergoing IST. Together with previous reports, our findings suggest that AA patients do not necessarily have a higher risk of severe COVID-19 compared with the general population. Future investigations are needed to determine the optimal management for these patients and the ability of patients with AA to produce sufficient protective antibodies.