Humoral and cellular immune responses after 6 months of a heterologous SARS-CoV-2 booster with the protein-based PHH-1V vaccine in a phase IIb trial

Abstract

Covid-19; Heterologous booster; Protein-based vaccine

Covid-19; Refuerzo heteróloga; Vacuna basada en proteínas

Covid-19; Reforç heteròleg; Vacuna basada en proteïnes

The HIPRA-HH-2 was a multicentre, randomized, active-controlled, double-blind, non-inferiority phase IIb clinical trial comparing the immunogenicity and safety of the PHH-1V adjuvanted recombinant vaccine as a heterologous booster against homologous booster with BNT162b2. Interim results demonstrated strong humoral and cellular immune response against the SARS-CoV-2 Wuhan-Hu-1 strain and the Beta, Delta, and Omicron BA.1 variants up to day 98 post-dosing. Here we report that these responses with PHH-1V are sustained up to 6 months, including in participants over 65 years, despite their smaller sample size. The PHH-1V booster was non-inferior in eliciting neutralizing antibodies for SARS-CoV-2 Omicron XBB.1.5 variant compared to BNT162b2 after 6 months. No severe COVID-19 cases occurred in any group, and mild cases were similar (50.4 % for PHH-1V vs. 47.8 % for BNT162b2). While both groups may have reached comparable immunity levels, these findings suggest that the PHH-1V vaccine provides long-lasting immunity against various of SARS-CoV-2 variants. ClinicalTrials.gov Identifier: NCT05142553.

This study was sponsored by HIPRA SCIENTIFIC, S.L.U. (HIPRA) and partially funded by the Centre for the Development of Industrial Technology (CDTI, IDI-20211192), a public organisation answering to the Spanish Ministry of Science and Innovation. HIPRA was involved in the study design; in the collection, analysis, and interpretation of data; in writing of the report; and in the decision to submit the paper for publication.