An investigational vaccine designed to protect against the B.1.351 SARS-CoV-2 variant has been administered as part of a new Phase 1 clinical trial evaluating the vaccine candidate’s safety and immunogenicity in adult volunteers. The vaccine, known as mRNA-1273.351, was developed by the biotechnology company ModernaTX, Inc., based in Cambridge, Massachusetts. The trial is led and funded by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health. The trial will enroll approximately 210 healthy adult volunteers at four clinical research sites in the United States that are part of the NIAID-funded Infectious Diseases Clinical Research Consortium (IDCRC).


“The B.1.351 SARS-CoV-2 variant, first identified in the Republic of South Africa, has been detected in at least nine states in the United States,” said NIAID Director Anthony S. Fauci, M.D. “Preliminary data show that the COVID-19 vaccines currently available in the United States should provide an adequate degree of protection against SARS-CoV-2 variants. However, out of an abundance of caution, NIAID has continued its partnership with Moderna to evaluate this variant vaccine candidate should there be a need for an updated vaccine.”

Investigators from NIAID and Moderna co-developed the mRNA-1273 vaccine, which is currently authorized by the U.S. Food and Drug Administration for emergency use in the United States for the prevention of COVID-19 in adults 18 years of age and older. The vaccine is administered as two 100-microgram (mcg) doses 28 days apart. The vaccine uses lipid nanoparticles to deliver instructions to the body’s cells for making a stabilized version of the spike protein found on the surface of the SARS-CoV-2 virus. After the vaccination, the immune system detects the stabilized spike protein and begins building a response against the virus. The variant vaccine candidate developed by Moderna, mRNA-1273.351, differs from the currently-authorized Moderna vaccine in that it delivers instructions for making the SARS-CoV-2 spike that incorporates key mutations in the B.1.351 virus variant. In addition to the Phase 1 clinical trial, investigators at NIAID’s Vaccine Research Center are collaborating with Moderna to evaluate mRNA-1273.351 in animal models.

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