Coronavirus vaccine makers led gains in healthcare stocks last year. And the trend didn't stop as the world rang in the new year. Many of these companies charged full speed ahead into 2021. And for good reason. Some of them began generating revenue from vaccines. Others moved closer to bringing a potential vaccine to market.

But recently, excitement around some of the biggest winners has started to fade. Now, the big question is whether share price declines represent a buying opportunity -- or a sign to flee the stock. Let's take a look at three of the biggest movers.

Vaxart (NASDAQ:VXRT) skyrocketed more than 300% from the start of the year through Feb. 2. That's after last year's 1,500% gain. The biotech company is developing an oral COVID-19 vaccine. That potential product could be a game changer. Imagine a vaccine without a jab -- and the ease of transporting and storing a room-temperature-stable tablet.