The EMA issued a guidance Feb. 25 outlining the requirements for manufacturers planning to modify COVID-19 vaccines to address emerging variants of the SARS-CoV-2 coronavirus.

The guidance is based on the assumption that a modified vaccine would rely largely on the same technology and platform as the approved “parent” vaccine and any differences would be in the specific structure selected to trigger the immune response in the body.

To get the necessary clinical data, the EMA recommends sponsors conduct a randomized, controlled immunogenicity trial that investigates the immune response triggered by the variant vaccine against the variant virus compared with that of the original vaccine in a small group of participants.

“Large-scale safety and efficacy studies are not needed and moreover would present feasibility constraints,” the EMA said.

No further lab studies will be required, but manufacturers will need to generate data showing that the quality of the variant vaccine complies with the standards set for the parent.

If a multivalent vaccine is developed, the EMA said additional evidence may be necessary to ensure the quality of the active substances and the finished product.