mRNA-1769

mRNA-1769 is an investigational mRNA-based vaccine developed by Moderna for the prevention of mpox (monkeypox) and potentially smallpox. The vaccine encodes four proteins found on the surface of the monkeypox virus, delivered via lipid nanoparticles. Upon administration, these mRNAs are translated into viral proteins in host cells, stimulating an immune response that includes production of neutralizing antibodies and antigen-specific T cells. Preclinical studies have shown that mRNA-1769 provides enhanced protection against severe disease and reduces viral replication compared to existing vaccines such as Jynneos. The candidate has demonstrated cross-neutralization against multiple orthopoxviruses including vaccinia, cowpox, rabbitpox, camelpox, and ectromelia virus. As of 2024–2025, it is being evaluated in a Phase I/II clinical trial in healthy adults to assess safety, tolerability, and immunogenicity[2][3][5][6][8].