Humoral Immunogenicity of SARS-CoV-2 mRNA Primary Vaccination Among People with HIV.

People with HIV (PWH) may exhibit altered immune responses to SARS-CoV-2 vaccination due to persistent immune dysregulation despite antiretroviral therapy. We evaluated humoral immunogenicity following mRNA SARS-CoV-2 vaccination in PWH according to CD4 T-cell count and compared responses with HIV-negative controls. The study included 57 PWH stratified by CD4 count (<200 and ≥200 cells/µL), alongside 12 HIV-negative controls. Neutralizing antibody titers (NT50) against SARS-CoV-2 pseudoviruses expressing the D614G and Omicron BA.5 spike variants were measured using a luciferase-based neutralization assay one month (M1) and six months (M6) after primary vaccination with BNT162b2 or mRNA-1273. PWH with CD4 counts ≥ 200 cells/µL demonstrated higher neutralizing titers against D614G at M1 and M6, with significant differences observed between CD4 groups (M1: p = 0.03; M6: p = 0.02). Neutralization of BA.5 was lower overall; while no overall group differences were observed at M1, higher titers were detected among individuals with CD4 ≥ 200 cells/µL at six months (p = 0.04). Neutralizing titers correlated positively with CD4 counts among PWH. Responses were broadly comparable between PWH and HIV-negative controls and did not differ substantially by vaccine type. These findings indicate that immune status, reflected by CD4 T-cell count, is a key determinant of SARS-CoV-2 vaccine-induced humoral responses in PWH and support prioritizing vaccination strategies for individuals with advanced immunosuppression.