Novavax’s Shot Effective Against Covid in Final Trial Analysis

Novavax Inc.’s Covid-19 vaccine was 96.4% effective against mild, moderate and severe symptoms of the disease in the final analysis of a late-stage trial in the U.K.

Shares of the drugmaker were up 16% in after-hours trading Thursday in New York. Since the start of this year, the stock had gained more than 68% through Thursday’s close.

The company also released final results of a mid-stage trial from South Africa showing that its vaccine was 55.4% effective against a variant circulating there that’s already been shown to partially elude the effects of some shots. Both studies reached their statistical ...