• CD11a expressing lymphocytes (CD4+ and CD8+) and B cells were decreased in critically ill patients. Interestingly, it was suggested that T cell decline in circulation may be associated with increased infiltration of these cells toward the site of infection. Whereas recovered patients showed reduced decline in CD11a T cells. Thus, CD11a positive T cells were suggested as a possible prognostic marker of COVID-19.• Interestingly, eosinophil number was increased patients who were critically ill. Here, CD4 is linked to infection.