The NIH’s National Institute of Allergy and Infectious Diseases (NIAID) will soon begin a phase 1 clinical trial of Moderna’s variant-specific COVID-19 vaccine candidate, mRNA-1273.351, which has been tailored to better protect against the virus’ South African mutation. Moderna will also conduct trials of its own.

The drugmaker announced Wednesday that it has shipped doses of its modified COVID-19 vaccine to the NIH for evaluation in a phase 1 trial of the candidate. The NIAID, which is both leading and funding the research, will assess if the rejiggered vaccine can serve as a viable booster shot against the fast-spreading strain. The trial will kick off once the FDA has given its go-ahead.

Moderna, which first announced its efforts on a modified vaccine a month ago, said it is also spearheading its own clinical studies to support regulatory filings for any booster shot or updates to its primary vaccine. It plans to evaluate the modified vaccine on its own, the modified vaccine combined with the company’s original vaccine and a third shot of its original vaccine as a booster. It will also evaluate the original and modified vaccine combination as a primary vaccination for patients who are seronegative — meaning they don’t have antibodies against the virus in their blood serum.

The two-dose Moderna vaccine looks to have diminished efficacy against the South African mutation but appears to still offer protection. The company said that “while initial data confirm that [our] vaccine provides neutralizing activity against variants of concern,” it is taking action against viral mutations “out of an abundance of caution.”

“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,” said Moderna 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.”

The company intends to follow the FDA’s recently published guidance on amending Emergency Use Authorizations for modified vaccines by evaluating immunogenicity and safety in both nonvaccinated patients and patients who have received its vaccine. Peter Marks, director of the Center for Biologics Evaluation and Research, has said the agency expects modified vaccine trials to take around “two to three months” and consist of “a few hundred individuals” (DID, Feb. 23). — James Miessler