The new vaccine, mRNA 1273.351, is the first candidate out of Moderna’s program to tackle virus variants. A multivalent booster candidate – which combines the existing authorized vaccine with the new mRNA 1273.351 - is also set to follow.
The National Institute of Allergy and Infectious Diseases (NIAID), part of the NIH, will conduct the Phase 1 clinical trial to see if mRNA-1273.351 boosts immunity against the South Africa variant B.1.351.
The study will be initiated following the safe-to-proceed authorization from the FDA. Moderna will conduct its own clinical studies in parallel to support regulatory filings for any booster vaccine or updated primary vaccine.
Existing vaccine provides reduced protection
In January, an in vitro study showed that Moderna’s existing mRNA 1273 vaccine provides protection against strains that have emerged from South Africa and the UK. But while the data suggested almost equivalant neutralizing titers against the B.1.1.7 UK variant relative to prior variants, it did show reduced protection against the South Africa strain, with a six-fold reduction in neutralizing titers.
Given this reduced efficacy (which, however, remains above levels expected to offer protection) Moderna announced it was working on a new booster shot against B.1.351 ‘out of an abundance of caution’.
The company has now elaborated on this strategy for combating new variants. The first arm will explore the efficacy of new variant-specific vaccines as booster shots to the authorized mRNA 1273 vaccine.
The second arm will look at the potential of the new variant-specific vaccines as a stand-alone, two dose regimen at the 100 µg dose level and lower.
Strategy 1: evaluate three different vaccine boosters
- * 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.
Strategy 2: evaluate new variant-specific vaccines as stand-alone regimens
- mRNA-1273.351: which has been designed to combat the South Africa variant
- mRNA-1273.211: the multivalent vaccine combining mRNA-1273 and mRNA.351
These two candidates will be evaluated as a two-dose vaccine at 100 µg doses and lower. The authorized vaccine, mRNA-1273, is administered as two 100 µg doses.
Stéphane Bancel, Chief Executive Officer of Moderna, said: “As we seek to defeat COVID-19, we must be vigilant and proactive as new variants of SARS-CoV-2 emerge.
"Leveraging the flexibility of our mRNA platform, we are moving quickly to test updates to the vaccines that address emerging variants of the virus in the clinic. Moderna is committed to making as many updates to our vaccine as necessary until the pandemic is under control.
"We hope to demonstrate that booster doses, if necessary, can be done at lower dose levels, which will allow us to provide many more doses to the global community in late 2021 and 2022 if necessary.”