SARS-CoV-2 Variant Vaccine Boosters Trial: Preliminary Analyses

Area of Science:

• Vaccinology
• Immunology
• Infectious Diseases

Background:

• Waning immunity from SARS-CoV-2 vaccines necessitates updated vaccine formulations.
• Emerging Omicron subvariants pose a challenge to existing vaccine effectiveness.
• This study assessed the safety and immunogenicity of novel Moderna COVID-19 mRNA variant vaccines.

Approach:

• A Phase 2, open-label, randomized trial involved healthy adults with prior SARS-CoV-2 vaccination.
• Participants received one of six Moderna mRNA-1273 vaccine regimens, including prototype, Omicron BA.1-containing, and bivalent candidates.
• Neutralizing antibody titers against various SARS-CoV-2 variants and subvariants were measured 15 days post-vaccination.

Key Points:

• All tested Moderna COVID-19 mRNA vaccines were safe and well-tolerated.
• Omicron BA.1-containing vaccines elicited higher neutralizing antibody titers against Omicron BA.1 compared to the prototype vaccine.
• Antibody responses against Omicron BA.4/BA.5 subvariants were lower than those against Omicron BA.1 for all vaccine groups.

Conclusions:

• Updated mRNA vaccines incorporating Omicron BA.1 components enhance immune responses against this specific variant.
• The observed reduction in antibody titers against Omicron BA.4/BA.5 highlights the ongoing challenge of variant evolution.
• Further research is needed to optimize vaccine strategies against rapidly evolving SARS-CoV-2 variants.