Novavax (NASDAQ: NVAX) has said that its Covid-19 shot is 89.3% effective, based on interim data from its phase 3 clinical trials conducted in the U.K. [ 1 ] The company expects to file for emergency authorization with U.K. regulators in the coming months. While the reported efficacy numbers seem to put the vaccine slightly behind Pfizer (NYSE: PFE) and Moderna (NASDAQ: MRNA), who have rolled out vaccines that are roughly 95% effective, we think the Novavax shot holds more promise for a couple of reasons.