Regulators recently approved an updated COVID shot from Novavax. Struggling biotech Novavax (NVAX -0.72%) was a hot buy a few years ago as it was in the midst of developing a vaccine for COVID-19. Ultimately, it did produce an approved vaccine, but it was a bit late and did not end up generating nearly as much in revenue as it could have if it had obtained approval much earlier. And since 2022, a sell-off has ensued, with the stock losing more than 91% of its value. Recently, there's been some renewed excit ...