Lymphocyte Subsets in Mild COVID-19

We read the publication on “Lymphocyte Subsets in Mild COVID-19 Pediatric Patients¹” and would like to correspond to this report. According to Argun et al.¹ an increase in several lymphocyte subsets such as natural killer cells, T cells, and CD4+ T cells may be one reason for mild severe acute respiratory syndrome coronavirus 2 infections in children. We agree that the response to the COVID-19 in the pediatric population might or might not be different from the adult population. The present study focused on lymphocyte subset parameters. The investigation on CD4+ in COVID-19 was firstly performed when the disease early emerged and the low CD4+ count was observed.² The results contrast with the current observation that the CD4+ is increased.¹ Several background conditions might determine the different CD4+ count levels. The health/immunological background before the infection is usually not available in the reports, and it might be the important determinant for CD4+ count level during COVID-19 illness. Also, the given therapy to the patient for the management of COVID-19 might also affect the CD4+ count level. These factors should be recognized.