COVID Mutants: Vaccine Changes Likely To Need Immunogenicity Studies, Not Big Efficacy Trials

US FDA considering approach that is similar to, but more stringent than, influenza strain changes, CBER Director Marks says. Meanwhile, vaccine developers face challenge of when to change antigens to get the best results, NIH’s Graham notes. As FDA and sponsors gain more experience with tweaking the vaccines to account for new coronavirus variants and strains, the process may be expedited further.