Currently, Moderna is just one of three companies (the others being drugmakers Johnson & Johnson and Pfizer ) with COVID-19 vaccines that are available for use in the U.S. market. But there could soon be another, from vaccine maker Novavax. That company plans to apply for Emergency Use Authorization (EUA) from the U.S. Food and Drug Administration for its vaccine before the year is over. If that happens, expect some downgrades from analysts, as it could be a sign that market share for Moderna will shrink in the U.S.; Novavax may even become the better stock to buy.