The Novavax vaccine works by combining a purified spike protein with an adjuvant, or a substance designed to enhance a given immune response.
It is an old technology, but arguably the most direct line of attack we can mount against a virus. Other FDA-approved Covid-19 vaccines employ methods that are certainly innovative and still effective, but on the whole more roundabout approaches to hitting the same target. These include the messenger RNA in the Moderna and Pfizer-BioNTech vaccines, which instruct human cells to make spike proteins, and the adenovirus vectors in the Johnson & Johnson and AstraZeneca vaccines, which carry instructions for creating anti-SARS-CoV-2 antibodies.
That the clinical trials for the Novavax vaccine have yielded such promising results is a great sign, especially given the rise of new variants.