Anti-Spike Antibodies and Neutralising Antibody Activity in People Living with HIV Vaccinated with COVID-19 mRNA-1273 Vaccine: A Prospective Cohort Study

Background: Vaccines against COVID-19 are a powerful tool to control the current SARS-CoV-2 pandemic. A thorough description of their immunogenicity among people living with HIV (PLWHIV) is necessary. We aimed to assess the immunogenicity of the mRNA-1273 vaccine among PLWHIV. Methods: In this prospective cohort, adult PLWHIV outpatients were enrolled during the Italian vaccination campaign. Enrolment was allowed irrespective of ongoing combination antiretroviral therapy (ART), plasma HIV viral load and CD4+ T cell count. A two-dose regimen of mRNA-1273, with administrations performed 28 days apart, was employed. The primary outcomes were anti-spike (anti-S) antibody titres and neutralising antibody activity, assessed 28 days after completing the vaccination schedule, compared with individuals not affected by HIV (referred as healthy-donors, HDs).   Findings: CD4+ T cell count groups and anti-nucleocapside (anti-N) positive serology were the only variables associated with anti-spike (anti-S) antibody titres (expressed as U/mL) and neutralising antibody activity. Anti-S antibodies were higher in COVID-19-experienced PLWHIV (median 12500 U/mL IQR [5704-12500]) than in COVID-19-naive PLWHIV (median 2437 U/mL IQR [1485-4526]) but did not differ from those observed in COVID-19-experienced HDs (median 1077 U/mL IQR [702-7551]). Neutralising antibody activity in sera was higher in COVID-19-experienced PLWHIV (median 10888 IQR [2478-14416]) compared to COVID-19-naive PLWHIV (median 1192 IQR [742-2421]) but was comparable to those observed in COVID-19-experienced HDs (median 20959 U/mL IQR [10060-31857]). When stratified according to CD4+ T cell count ( 500 cells/μL), anti-S antibody titres (median 2173 U/mL [IQR 897-4109], 5763 IU/mL [IQR 4801-12500], 2449 U/mL [IQR 1524-5704]) were not lower to those observed among HDs (median 1425 U/mL [IQR 599-6131]). In addition, neutralising antibody activity, stratified according to the CD4+ T cell count (median 1314 [IQR 606-2477], 3329 IU/mL [IQR 1905-10508], 1227 U/mL [IQR 761-3032]), was similar to those displayed by HDs (median 2112 U/mL [IQR 719-8889]). Interpretation: Inoculation with mRNA-1273 vaccine given 4 weeks apart produced adequate immune responses in PLWHIV, who are well controlled on ART, irrespective of CD4+ T cell count and equivalent to individuals without HIV infection, supporting vaccination in PLWHIV. Funding: This study was partially supported by Italian Ministry of Health Ricerca Corrente 2021 and Grant Ricerca Finalizzata GR 2018-12365699, by Intesa San Paolo COVID-19 emergency 2020 funds, and by Fondazione Cariplo (INNATE-CoV). Declaration of Interest: All other authors declare no competing interests. Ethical Approval: The study protocol (286_2021) was approved by the INMI “Lazzaro Spallanzani” Ethics Committee (Roma, Italy),