Background The safety and immunogenicity of the bivalent omicron-containing mRNA-1273.214 booster vaccine are not known. Methods In this ongoing, phase 2–3 study, we compared the 50-μg bivalent vaccine mRNA-1273.214 (25 μg each of ancestral Wuhan-Hu-1 and omicron B.1.1.529 [BA.1] spike messenger RNAs) with the previously authorized 50-μg mRNA-1273 booster. We administered mRNA-1273.214 or mRNA-1273 as a second booster in adults who had previously received a two-dose (100-μg) primary series and first booster (50-μg) dose of mRNA-1273 (≥3 months earlier). The primary objectives were to assess the safety, reactogenicity, and immunogenicity of mRNA-1273.214 at 28 days after the booster dose. Results Interim results are presented. Sequential groups of participants received 50 μg of mRNA-1273.214 (437 participants) or mRNA-1273 (377 participants) as a second booster dose. The median time between the first and second boosters was similar for mRNA-1273.214 (136 days) and mRNA-1273 (134 days). In participants with no previous severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, the geometric mean titers of neutralizing antibodies against the omicron BA.1 variant were 2372.4 (95% confidence interval [CI], 2070.6 to 2718.2) after receipt of the mRNA-1273.214 booster and 1473.5 (95% CI, 1270.8 to 1708.4) after receipt of the mRNA-1273 booster. In addition, 50-μg mRNA-1273.214 and 50-μg mRNA-1273 elicited geometric mean titers of 727.4 (95% CI, 632.8 to 836.1) and 492.1 (95% CI, 431.1 to 561.9), respectively, against omicron BA.4 and BA.5 (BA.4/5), and the mRNA-1273.214 booster also elicited higher binding antibody responses against multiple other variants (alpha, beta, gamma, and delta) than the mRNA-1273 booster. Safety and reactogenicity were similar with the two booster vaccines. Vaccine effectiveness was not assessed in this study; in an exploratory analysis, SARS-CoV-2 infection occurred in 11 participants after the mRNA-1273.214 booster and in 9 participants after the mRNA-1273 booster. Conclusions The bivalent omicron-containing vaccine mRNA-1273.214 elicited neutralizing antibody responses against omicron that were superior to those with mRNA-1273, without evident safety concerns. (Funded by Moderna; ClinicalTrials.gov number, NCT04927065 .)

Background Updated vaccination strategies against acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern are needed. Interim results of the safety and immunogenicity of the bivalent omicron-containing mRNA-1273.214 booster candidate are presented. Methods In this ongoing, phase 2/3 trial, the 50-μg bivalent vaccine mRNA-1273.214 (25-μg each ancestral Wuhan-Hu-1 and omicron B.1.1.529 spike SARS-CoV-2 mRNAs) was compared to the authorized 50-μg mRNA-1273 booster in adults who previously received 2-dose primary series of 100-μg mRNA-1273 and a first booster dose of 50-μg mRNA-1273 at least 3 months prior. Primary objectives were safety and reactogenicity, and immunogenicity of 50-μg mRNA-1273.214 compared with 50-μg mRNA-1273. Immunogenicity data 28 days after the booster dose are presented. Results Four hundred thirty-seven and 377 participants received 50-μg of mRNA-1273.214, or mRNA-1273, respectively. Median time between first and second booster doses of mRNA-1273.214 and mRNA-1273 were similar (136 and 134 days, respectively). In participants with no prior SARS-CoV-2 infection, observed omicron neutralizing antibody geometric mean titers (GMTs [95% confidence interval]) after the mRNA-1273.214 and mRNA-1273 booster doses, were 2372.4 (2070.6−2718.2) and 1473.5 (1270.8−1708.4) respectively and the model-based GMT ratio (97.5% confidence interval) was 1.75 (1.49−2.04). All pre-specified non-inferiority (ancestral SARS-CoV-2 with D614G mutation [D614G] GMT ratio; ancestral SARS-CoV-2 [D614G] and omicron seroresponse rates difference) and superiority primary objectives (omicron GMT ratio) for mRNA-1273.214 compared to mRNA-1273 were met. Additionally, mRNA-1273.214 50-μg induced a potent neutralizing antibody response against omicron subvariants BA.4/BA.5 and higher binding antibody responses against alpha, beta, gamma, delta and omicron variants. Safety and reactogenicity profiles were similar and well-tolerated for both vaccines groups. Conclusion The bivalent vaccine mRNA-1273.214 50-μg was well-tolerated and elicited a superior neutralizing antibody response against omicron, compared to mRNA-1273 50-μg, and a non-inferior neutralizing antibody response against the ancestral SARS-CoV-2 (D614G), 28 days after immunization, creating a new tool as we respond to emerging SARS-CoV-2 variants.

We previously presented day 29 interim safety and immunogenicity results from a phase 2/3 study comparing the Omicron-BA.1-containing bivalent vaccine mRNA-1273.214 (50-µg) to the 50-µg mRNA-1273 booster in adults who previously received the mRNA-1273 primary series (100-µg) and mRNA-1273 first booster (50-µg) dose. Here we present day 91 post-booster results. Participants were sequentially enrolled to receive 50-µg of mRNA-1273 (n = 376) or mRNA-1273.214 (n = 437) as second booster doses. In participants with no pre-booster severe acute respiratory syndrome coronavirus 2-infection (SARS-CoV-2), mRNA-1273.214 elicited Omicron-BA.1-neutralizing antibody titers that were significantly higher (964.4 [834.4-1114.7]) than those of mRNA-1273 (624.2 [533.1-730.9]) and similar between boosters against ancestral SARS-CoV-2 at day 91. mRNA-1273.214 also induced higher binding antibody responses against Omicron BA.1 and alpha, gamma and delta variants than mRNA-1273. Safety profiles were similar for both vaccines. The Omicron-BA.1 bivalent vaccine induced improved antibody persistence compared to mRNA-1273.

Background Vaccination strategies that provide enhanced immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants are needed. We evaluated the safety and immunogenicity of a bivalent omicron containing vaccine, mRNA-1273.214 (50 µg), administered as a second booster dose in adult participants. Methods In this ongoing phase 2/3 trial, 50 µg of the bivalent vaccine mRNA-1273.214 (25 µg each ancestral Wuhan-Hu-1 and omicron BA.1 spike mRNAs) or 50 µg of the authorized mRNA-1273 were administered as second boosters in adults who previously received a 2 dose (100 µg) primary series and a first booster (50 µg) dose of mRNA-1273 (≥ 3 months prior). Primary objectives were safety and reactogenicity and immunogenicity 28 days post-booster dose. Results In participants with no prior SARS-CoV-2 infection who received booster doses of mRNA-1273.214 (n=334) or mRNA-1273 (n=260), neutralizing antibody (nAb) geometric mean titers (GMTs [95% confidence interval (CI)]) against omicron BA.1 were 2372.4 (2070.6−2718.2) and 1473.5 (1270.8−1708.4), respectively. The model-based GMT ratio (GMR [97.5% CI]) of mRNA-1273.214 compared to mRNA-1273 was 1.75 (1.49−2.04), meeting the pre-specified superiority criterion against omicron BA.1. The pre-specified criterion for non-inferiority against the ancestral SARS-CoV-2 strain was also met. Additionally, mRNA-1273.214 elicited higher GMTs (727.4 [632.8−836.1]) than mRNA-1273 (492.1 [431.1−561.9]) against omicron subvariants BA.4/BA.5 [GMR (95% CI) 1.69 [1.51−1.90])]. Binding antibody responses against alpha, beta, gamma, delta, and omicron were numerically higher in the mRNA-1273.214 group compared to mRNA-1273. mRNA-1273.214 GMTs were consistently higher across age (18-< 65 and ≥ 65 years) and pre-booster SARS-CoV-2 infection subgroups (Figure). Safety and reactogenicity were similar for both vaccine groups. Conclusion The bivalent omicron containing mRNA-1273.214 elicited superior nAb responses against omicron 28 days post-immunization compared to mRNA-1273 regardless of age and prior SARS-CoV-2 infection; no new safety concerns were identified. Disclosures Spyros Chalkias, MD, Moderna, Inc.: Salary|Moderna, Inc.: Stocks/Bonds Stephen R. Walsh, MD, Janssen Vaccines: Grant/Research Support|Moderna, Inc.: Grant/Research Support|NIAID/NIH: Grant/Research Support|Sanofi Pasteur: Grant/Research Support Nichole McGhee, B.S., Moderna, Inc.: Salary|Moderna, Inc.: Stocks/Bonds Joanne Tomassini, Ph.D., Moderna, Inc.: Advisor/Consultant Xing Chen, Sc.D., Moderna, Inc.: Salary|Moderna, Inc.: Stocks/Bonds Ying Chang, M.S., Moderna, Inc.: Salary|Moderna, Inc.: Stocks/Bonds Andrea Sutherland, M.D., MPH, Moderna, Inc.: Salary|Moderna, Inc.: Stocks/Bonds David Montefiori, Ph.D., Moderna, Inc.: Grant/Research Support Bethany Girard, Ph.D., Moderna, Inc.: Salary|Moderna, Inc.: Stocks/Bonds Darin Edwards, Ph.D., Moderna, Inc.: Salary|Moderna, Inc.: Stocks/Bonds Jing Feng, M.S., Moderna, Inc.: Salary|Moderna, Inc.: Stocks/Bonds Honghong Zhou, Ph.D., Moderna, Inc.: Salary|Moderna, Inc.: Stocks/Bonds Lindsey R. Baden, MD, Moderna, Inc.: Grant/Research Support|NIAID: Grant/Research Support Jacqueline Miller, MD, Moderna, Inc.: Salary|Moderna, Inc.: Stocks/Bonds Rituparna Das, M.D., Moderna, Inc.: Salary|Moderna, Inc.: Stocks/Bonds.