Safety and immunogenicity of a mosaic vaccine booster against Omicron and other SARS-CoV-2 variants:a randomized phase 2 trial

An ongoing randomized,double-blind,controlled phase 2 trial was conducted to evaluate the safety and immunogenicity of a mosaic-type recombinant vaccine candidate,named NVSI-06-09,as a booster dose in subjects aged 18 years and older from the United Arab Emirates(UAE),who had administered two or three doses of inactivated vaccine BBIBP-CorV at least 6 months prior to enrollment.The participants were randomly assigned with 1:1 to receive a booster dose of NVSI-06-09 or BBIBP-CorV.The primary outcomes were immunogenicity and safety against severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)Omicron variant,and the exploratory outcome was cross-immunogenicity against other circulating strains.Between May 25 and 30,2022,516 adults received booster vaccination with 260 in NVSI-06-09 group and 256 in BBIBP-CorV group.Interim results showed a similar safety profile between two booster groups,with low incidence of adverse reactions of grade 1 or 2.For immunogenicity,by day 14 post-booster,the fold rises in neutralizing antibody geometric mean titers(GMTs)from baseline elicited by NVSI-06-09 were remarkably higher than those by BBIBP-CorV against the prototype strain(19.67 vs 4.47-fold),Omicron BA.1.1(42.35 vs 3.78-fold),BA.2(25.09 vs 2.91-fold),BA.4(22.42 vs 2.69-fold),and BA.5 variants(27.06 vs 4.73-fold).Similarly,the neutralizing GMTs boosted by NVSI-06-09 against Beta and Delta variants were also 6.60-fold and 7.17-fold higher than those by BBIBP-CorV.Our findings indicated that a booster dose of NVSI-06-09 was well-tolerated and elicited broad-spectrum neutralizing responses against divergent SARS-CoV-2 variants,including Omicron and its sub-lineages.

Immunogenicity and safety of NVSI-06-07 as a heterologous booster after priming with BBIBP-CorV:a phase 2 trial

The increased coronavirus disease 2019(COVID-19)breakthrough cases pose the need of booster vaccination.We conducted a randomised,double-blinded,controlled,phase 2 trial to assess the immunogenicity and safety of the heterologous prime-boost vaccination with an inactivated COVID-19 vaccine(BBIBP-CorV)followed by a recombinant protein-based vaccine(NVSI-06-07),using homologous boost with BBIBP-CorV as control.Three groups of healthy adults(600 individuals per group)who had completed two-dose BBIBP-CorV vaccinations 1–3 months,4–6 months and≥6 months earlier,respectively,were randomly assigned in a 1:1 ratio to receive either NVSI-06-07 or BBIBP-CorV boost.Immunogenicity assays showed that in NVSI-06-07 groups,neutralizing antibody geometric mean titers(GMTs)against the prototype SARS-CoV-2 increased by 21.01–63.85 folds on day 28 after vaccination,whereas only 4.20–16.78 folds of increases were observed in control groups.For Omicron variant,the neutralizing antibody GMT elicited by homologous boost was 37.91 on day 14,however,a significantly higher neutralizing GMT of 292.53 was induced by heterologous booster.Similar results were obtained for other SARS-CoV-2 variants of concerns(VOCs),including Alpha,Beta and Delta.Both heterologous and homologous boosters have a good safety profile.Local and systemic adverse reactions were absent,mild or moderate in most participants,and the overall safety was quite similar between two booster schemes.Our findings indicated that NVSI-06-07 is safe and immunogenic as a heterologous booster in BBIBP-CorV recipients and was immunogenically superior to the homologous booster against not only SARS-CoV-2 prototype strain but also VOCs,including Omicron.