1954. Immunogenicity against SARS CoV-2 ancestral strain and variants of two new COVID-19 recombinant adjuvanted vaccines compared to BNT162b2 as a third dose following two doses of BNT162b2: a single-blinded multicenter randomized controlled trial

Abstract Background New adjuvanted recombinant protein vaccines against coronavirus disease 2019 (COVID-19) as heterologous boosters could maximize the benefits of vaccination SARS CoV-2. Methods In this randomized, single-blinded, multicenter trial, adults who had received two doses Pfizer-BioNTech mRNA vaccine (BNT162b2) 3–7 months before were randomly assigned to receive a boost BNT162b2, Sanofi/GSK SARS-CoV-2 MV D614 (monovalent parental formulation) or B.1.351 Beta formulation). The primary endpoint was percentage subjects with ≥ 10-fold increase in neutralizing antibody titers for Wuhan (D614) and (Beta) viral strains between D0 D15. Results percentages participants whose strain increased by factor 10 Day 0 15 55.3% (95% CI 43.4-66.7) MV(D614) group (n=76), 76.1% (64.5-85.4) MV(Beta) (n=71) 63.2% (51.3-73.9) BNT162b2 (n=76). These 44.7% (33.3-56.6), 84.5% (74.0-92.0) 51.3% (39.6-63.0) strain, respectively. Higher antibodies rates Delta Omicron BA.1 variants also elicited after compared other vaccines. Comparable reactogenicity profile observed three Table 1.Characteristics patients at inclusion (per-protocol population).Figure 2.Neutralizing (wild-type; Wuhan) Beta, D0, D15 D28 dose (“post D3”)with Sanofi/GSK-D614, Sanofi/GSK-B.1.351 population); dotted line represents positivity threshold.Figure 4.Rates grades severity solicited adverse events reported from D7 randomized groups safety population (G1, Sanofi/GSK-D614; G2, Sanofi/GSK-B.1.351; G3, BNT162b2) according Toxicity Grading Scale Healthy Adult Adolescent Volunteers Enrolled Preventive Vaccine Clinical Trials (Modified FDA scale/September 2007) Conclusion All boosted response initial course. Heterologous boosting (Beta provided higher variants, including BA.1, vaccine. Disclosures Odile Launay, MD, PhD, AstraZeneca: Financial|GlaxoSmithKline: Advisor/Consultant|GlaxoSmithKline: Grant/Research Support|Johnson & Johnson: Advisor/Consultant|Johnson Support|MD: Advisor/Consultant|Moderna: Advisor/Consultant|MSD: Data monitoring board|Pfizer: Advisor/Consultant|Pfizer: Support|Sanofi Pasteur: Advisor/Consultant|Sanofi board Liem Binh Luong, Pfizer: Honoraria Karine Lacombe, Gilead: Advisor/Consultant|Janssen: Support|MSD: Support|ViiV Healthcare: Support Elisabeth Botelho-Nevers, PHD, Janssen: Board Member|Pfizer: Member|Sanofi Member.