$NVAX Moderna's market cap stands close to $130 billion -- roughly 6.5 times its expected sales. By comparison, Novavax's market cap is less than $12.5 billion -- only 2.2 times its expected 2022 sales. My view is that Novavax's near-term catalysts and more attractive valuation make it the better vaccine stock to buy right now. However, I think that Moderna's mRNA technology could give it a major advantage over the long term.