Moderna's variant-specific COVID-19 vaccine candidate ready for clinical testing

Moderna said Wednesday that it has manufactured the initial batch of an updated version of its COVID-19 vaccine designed to better protect against the B.1.351 variant of SARS-CoV-2 first identified in South Africa. The company indicated late last month that it would be working on the variant-specific booster candidate after its original vaccine mRNA-1273 produced a six-fold decrease in neutralising antibodies with the B.1.351 strain relative to prior variants.

Doses of this new candidate, dubbed mRNA-1273.351, have been shipped to the US National Institute of Allergy and Infectious Diseases for testing in a Phase I clinical trial pending a greenlight from the FDA.

Booster, primary vaccination strategies

Moderna said it also plans to evaluate two other approaches to boosting as a possible means of revving up immunity against worrisome SARS-CoV-2 mutations. These include a multivalent booster candidate, referred to as mRNA-1273.211, which combines mRNA-1273 plus mRNA-1273.351 in a single vaccine at the 50-mcg dose level and lower. The current protocol for mRNA-1273 calls for two doses of 100 mcg. In addition, Moderna said it will assess the benefits of adding a third dose of mRNA-1273 as a booster at the 50-mcg level, adding it has already begun dosing this cohort.

Aside from this booster strategy, the company said it also plans to experiment using mRNA-1273.351 and mRNA-1273.211 as primary vaccinations against COVID-19 in seronegative individuals, administering the two-dose regimens at the 100-mcg dose level and lower. In parallel with the NIAID study, Moderna said it would be conducting its own clinical studies to support regulatory filings for any booster or updated primary vaccine. Moreover, to align with recent FDA advice on vaccine development targeting emerging strains, Moderna says it will be evaluating immunogenicity and safety in both non-vaccinated individuals and those who previously received mRNA-1273.

"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," commented CEO Stéphane Bancel. "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," he added.

Expanding production

Separately, Moderna said Wednesday that new investments in its manufacturing facilities is allowing it to boost production capacity, with the company now expecting to make about 1.4 billion doses of its COVID-19 vaccine in 2022, at the 100-mcg dose. "Given a six- to nine-month timeframe to add capacity and an additional timeframe to permit regulatory validation and ramp-up, it is estimated that up to 12 months may be necessary before the additional production is available," it said. The output could be higher if production includes making vaccines at lower doses. The company estimates that if it can dedicate its entire 2022 capacity to a 50-mcg booster, it could produce up to 2.8 billion doses in fiscal 2022.

Meanwhile, for this year, Moderna raised the low end of its projected production to 700 million doses from 600 million previously, and the company continues to target supplying up to 1 billion doses.

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