Some Novavax shareholders were probably feeling pretty good in the early days of September. While the stock had lost nearly half of its value year to date in May, most of that loss had been recovered in the subsequent months. But on Sept. 15, Novavax announced the stunning news that its RSV F vaccine, against a virus that causes acute respiratory disease, didn’t prove to be effective for older adults in the phase 3 Resolve trial. Shares plunged more than 80% overnight.
