Moderna has shipped its variant-specific vaccine candidate, mRNA-1273.351, to the National Institutes of Health (NIH) for a phase 1 clinical trial.

The NIH’s National Institute of Allergy and Infectious Diseases (NIAID) will evaluate the vaccine candidate against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant, B.1.351, first identified in the Republic of South Africa. 

According to data recently published in the New England Journal of Medicine, vaccination with mRNA-1273, Moderna’s FDA-authorized coronavirus disease 2019 (COVID-19) vaccine, produced neutralizing titers against all key emerging variants tested, including those identified in the UK (B.1.1.7 variant) and the Republic of South Africa (B.1.351 variant). The study showed no significant impact on neutralizing titers against the B.1.1.7 variant relative to prior variants; however, a 6-fold reduction in pseudovirus neutralizing antibody titers was observed with the B.1.351 variant.

“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,” said Stéphane Bancel, Chief Executive Officer of Moderna.

In a statement, the Company outlined their strategy for addressing the SARS-CoV-2 variants of concern. This includes testing of the following boosters:  a variant-specific booster candidate, mRNA-1273.351 at a dose of 50µg or lower; a multivalent booster candidate, mRNA-1273.211, which combines mRNA-1273 and mRNA-1273.351 in a single vaccine at a dose of 50µg dose or lower; and a third dose of mRNA-1273 as a booster at the 50µg dose level. Currently, the mRNA-1273 (100μg) vaccine is authorized as a 2-dose series given 28 days apart.

The Company also plans to evaluate mRNA-1273.351 and mRNA-1273.211 as a primary vaccination series (2-dose series at a dose of 100µg or lower) for those who are seronegative.

“Moderna is committed to making as many updates to our vaccine as necessary until the pandemic is under control,” said 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.”

In addition to the NIAID study, the Company will be conducting its own clinical trials to support regulatory filings for the booster vaccines and updates to the primary series.


Moderna announces it has shipped variant-specific vaccine candidate, mRNA-1273.351, to NIH for clinical study. [press release]. February 24, 2021.