The US Food and Drug Administration released guidance Feb. 22 that outlines how vaccines, drugs, and diagnostics can be modified, tested, and approved to address emerging variants of the SARS-CoV-2 virus. Two days later, Moderna announced that it is ready to begin clinical trials of a version of its vaccine tailored to the B.1.351 variant, first identified in South Africa, pending FDA review. For vaccines, the updated guidance covers manufacturing, nonclinical, and clinical requirements for modified versions of authorized vaccines. Although initial authorizations require large and long-term efficacy trials, the agency says it will green-light updated vaccines on the basis of smaller trials assessing immune response. These trials will require vaccination of only “a few hundred individuals” and will take “a few months” to complete, Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, said in a press conference. This approach draws on experience with seasonal influenza vaccines, which are updated annually. Once developers have a better understanding of the activity of their candidates, the agency may eventually further shorten the evaluation of modified COVID-19 vaccines, Marks suggested. The FDA has not yet defined how it will decide when COVID-19 vaccines need to be updated. The agency also released recommendations to guide the development of monoclonal antibodies, other drugs and biologics, and COVID-19 tests that can address emerging variants.
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