The ongoing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic and heterologous immunization approaches implemented worldwide for booster doses call for diversified vaccine portfolios. GRAd-COV2 is a gorilla adenovirus-based COVID-19 vaccine candidate encoding prefusion-stabilized spike. The safety and immunogenicity of GRAd-COV2 is evaluated in a dose-and regimen-finding phase 2 trial (COVITAR study, ClinicalTrials.gov: NCT04791423) whereby 917 eligible participants are randomized to receive a single intramuscular GRAd-COV2 administration followed by placebo, or two vaccine injections, or two doses of placebo, spaced over 3 weeks. Here, we report that GRAd-COV2 is well tolerated and induces robust immune responses after a single immunization; a second administration increases binding and neutralizing antibody titers. Potent, variant of concern (VOC) cross-reactive spike-specific T cell response peaks after the first dose and is characterized by high frequencies of CD8s. T cells maintain immediate effector functions and high proliferative potential over time. Thus, GRAd vector is a valuable platform for ge-netic vaccine development, especially when robust CD8 response is needed.

GRAd-COV2 vaccine provides potent and durable humoral and cellular immunity to SARS-CoV-2 in randomized placebo-controlled phase 2 trial

Pellicciotta, Martina;
2023-01-01

Abstract

The ongoing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic and heterologous immunization approaches implemented worldwide for booster doses call for diversified vaccine portfolios. GRAd-COV2 is a gorilla adenovirus-based COVID-19 vaccine candidate encoding prefusion-stabilized spike. The safety and immunogenicity of GRAd-COV2 is evaluated in a dose-and regimen-finding phase 2 trial (COVITAR study, ClinicalTrials.gov: NCT04791423) whereby 917 eligible participants are randomized to receive a single intramuscular GRAd-COV2 administration followed by placebo, or two vaccine injections, or two doses of placebo, spaced over 3 weeks. Here, we report that GRAd-COV2 is well tolerated and induces robust immune responses after a single immunization; a second administration increases binding and neutralizing antibody titers. Potent, variant of concern (VOC) cross-reactive spike-specific T cell response peaks after the first dose and is characterized by high frequencies of CD8s. T cells maintain immediate effector functions and high proliferative potential over time. Thus, GRAd vector is a valuable platform for ge-netic vaccine development, especially when robust CD8 response is needed.
2023
CD4
CD8
COVID-19
Sars-CoV-2 vaccine
T cell response
immunological memory
neutralizing antibodies
phase 2 clinical trial
safety
simian adenoviral vector
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11699/93820
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