On May 21, 2021, Novavax announced participation in a mix-and-match (vaccine interchangeability) COVID-19 vaccine booster trial that led by the University Hospital Southampton NHS Foundation Trust and other UK National Institute for Health Research sites.

Novavax’ recombinant protein vaccine candidate, NVX-CoV2373, was one of seven COVID-19 vaccines studied to evaluate the potential for providing a booster dose from different manufacturers in people who had previously received two doses of an authorized vaccine.

This study assessed the safety and immune response against COVID-19 provided by these various vaccine schedules. The study began during the first week of June and received support from the UK government Vaccines Task Force (VTF) and Department of Health and Social Care (DHSC).