Novavax itself wasn’t immune from the downdraft it created, with the stock reversing a 9.5% gain on Monday to close down about 1%. The shot’s efficacy was better than Wall Street was expecting amid the spread of more resistant variants, and that’s raising the specter of new competition. Novavax now has “a viable alternative to mRNA vaccines,” like Pfizer and BioNTech or Moderna’s shots, an analyst at Jefferies said.

But with Novavax up 86% so far this year and after a more than 2,700% leap in 2020, it wasn’t enough to further bolster shares. Biotech stocks often climb ahead of highly watched catalysts, only to give back gains even after a positive update.