NVX-Cov2373 Novavax Covid-19 vaccine: A further analysis of its efficacy using multiple modes of expression.

A fifth vaccine against Covid-19, NVX-CoV2373 Nuvavoxid® (Novavax), a protein-based adjuvanted vaccine, was recently marketed in Europe. The main clinical trial before marketing concluded to a 'vaccine efficacy' of 89.7% without talking about other validated efficacy parameters. We further analysed the data of this clinical trial using the different validated methods of risk expression: absolute risks (AR), AR reduction (ARR) and number needed to treat (NNT). ARR and NNT values were 1.22% and 82, respectively, for an RR value of 0.10. Description of these parameters allowed defining some interesting characteristics of NVX-CoV2373 efficacy according to age, race, variant and coexisting illness. Finally, we ask that the results of clinical trials be systematically presented, using not only RR but also including AR, ARR and NNT.