Moderna to test a “multivalent” COVID vaccine as well as single-valent boosters

On Wednesday (Feb. 24) Moderna announced a new vaccine strategy against the variant B.1.351 (501Y.V2) now predominant in several nations in southern Africa, and identified in more than 40 nations, as well as multiple U.S. states. Part of this strategy is the first-ever “multivalent” vaccine candidate that “combines mRNA-1273, Moderna’s authorized vaccine against ancestral strains, and mRNA-1273.351 in a single vaccine at the 50 µg dose level and lower.”

As advocated here Jan. 31, multivalent vaccines should be developed against multivariant viruses to prevent re-infections, more variants and a prolonged pandemic.

Also on this IDSA Science Speaks site Dec. 22, a rationale was presented for concern regarding antibody-evasion by this variant B.1.351 (501Y.V2) first found in South Africa, due to Spike protein mutations E484K and K417N.

Of note, however, the updated guidance for COVID-19 vaccines from the FDA Feb. 22 focusing on virus variants in appendix 2 explicitly pertained to single-valent booster candidate vaccines.  On page 18 of 21 of this guidance, FDA stated (my boldtype added): “This document also does not address considerations for multivalent COVID-19 vaccines”. Thus, further FDA guidance on multivalent vaccine candidates is anticipated.

Moderna reported multivalent booster candidate as only one of its three approaches:

• “A variant-specific booster candidate, mRNA-1273.351, based on the B.1.351 variant first identified in the Republic of South Africa, at the 50 µg dose level and lower.
• A multivalent booster candidate, mRNA-1273.211, which combines mRNA-1273, Moderna’s authorized vaccine against ancestral strains, and mRNA-1273.351 in a single vaccine at the 50 µg dose level and lower.
• A third dose of mRNA-1273, the Moderna COVID-19 Vaccine, as a booster at the 50 µg dose level. The Company has already begun dosing this cohort with the booster.”