In a cohort study of 2,017 COVID-19 patients (955 patients with HIV) comparing SARS-CoV-2 specific antibody titers among people with or without HIV, lower anti-RBD IgG (percentage change -53%) and pseudovirus neutralizing antibody titers (percentage change -67%) were observed in HIV infected group (median CD4+ cell count = 452 cell/μL) compared to patients without HIV infection [55••]. Here, CD4 is linked to COVID-19.