Safety and immunogenicity of PHH-1V as booster vaccination through the Omicron era: results from a phase IIb open-label extension study up to 6 months

• DOI: 10.1101/2024.04.09.24305540
• Publication Date: 2024-04-13T03:25:10Z
• Authors: M.J. Lopez; M.M. Vazquez; M. Alvarez; J.R. Arribas; E. Arana-Arri; P. Muñoz; J. Navarro-Pérez; R. Ramos; J. Molto; S. Otero-Romero; I. Esteban; E. Aurrecoechea; R. Pomarol; M. Plana; R Perez-Caballero; L. Bernad; J.G. Prado; L. Riera-Sans; A. Soriano
• Keywords: Booster (rocketry); Open label

Abstract Background Phase IIb HIPRA-HH-2 study results showed that PHH-1V as first booster dose elicited a strong and sustained neutralising antibody response against various SARS-CoV-2 variants. Here, we report the safety immunogenicity of fourth most prevalent Omicron variants in Spain. Methods The open-label extension ( NCT05142553 ) evaluated subjects aged ≥18 years followed for 6 months. Subjects received 6–12 months after previous regime either two doses BNT162b2 plus third (Cohort 1) or three 2). Primary regulatory endpoint neutralisation titres (GMT) BA.1 on Day 14 used Cohort 2 vs initial study. was also investigated by GMTs Beta, Delta, BA.1, BA.4/5 XBB.1.5 Days 14, 98 182 post-immunisation overall population Cohorts 1 versus baseline. Safety assessed. Findings From September 2022, 288 n=106; n=182). A significant increase antibodies subvariant at observed from homologous with mRNA vaccine compared to heterologous (1739.02 4049.01; GMT ratio 0.43 (95% CI: 0.28; 0.65; p-value < 0.0001). induced statistically days immunisation all baseline [GMFR (95%CI) 6.96 (5.23, 9.25) Beta variant; 6.27 (4.79, 8.22) Delta 9.21 (5.57, 15.21) 11.80 (8.29, 16.80) variant 5.22 (3.97, 6.87) variant]. Titres remained significantly higher 3 post-vaccination. comparison revealed no differences frequent adverse events were injection site pain 1: 84.0%; 2: 77.5%) fatigue 17.9%; 29.1%). No experienced severe COVID-19 infection. Interpretation potent circulating BA.4/5, subvariants previously vaccinated regardless regimen. These findings suggest could be an appropriate strategy upcoming vaccination campaigns. Funding HIPRA SCIENTIFIC, S.L.U (HIPRA), Research context Unmet needs Immunity will continue community through widespread Despite this, individual level, humoral new is diminished both infected individuals. Booster strategies have demonstrated reduction risk not only infection but long persistent post-COVID manifestations. Furthermore, regimens offer broad responses. However, available evidence regarding platforms beyond mRNA-based vaccines currently limited. Evidence before this elicits high long-lasting levels studied, well cellular immunity response, when individuals receiving viral vector vaccines. data Spain time period. Added value dimeric adjuvanted delivered can induce primary (two 2)) confirm fourth-dose booster. This tolerated safe irrespective prior received. Implications advantages broad-spectrum different emerging COVID-19, suggesting