However, no significant differences were observed in the reinfection incidence in COVID-19 patients according to serology status (18.6% of seropositive and 21.1% of seronegative patients; p = 1.000) or according to the T-cell response (30.8% in patients <5 CD4+ blasts/μL and 16.3% in patients with ≥5 CD4+ blasts/μL; p = 0.256) (Table 3). Here, CD4 is linked to COVID-19.