What happened

Amusement park stocks rose sharply on Wednesday, as investors cheered news of progress toward the development of a COVID-19 vaccine.

By the close of trading, shares of SeaWorld (NYSE:SEAS), Six Flags (NYSE:SIX), and Cedar Fair (NYSE:FUN) were up 15%, 13%, and 7%, respectively.

So what 

Amusement park companies could benefit tremendously from a safe and effective vaccine for COVID-19. Health authorities have forced their parks to remain closed for much of the year due to concerns that large crowds could perpetuate the spread of the dangerous disease.

Worse still, even as some parks begin to reopen, they're unlikely to enjoy strong attendance. Many people will choose to forego vacations at crowded locations due to fears of getting sick.

People are smiling while riding a roller coaster.

Amusement park stocks rebounded on Wednesday. Image source: Getty Images.

Fortunately, theme park companies finally received some good news. An interim analysis of Moderna's phase 1 study for its experimental COVID-19 vaccine showed that it produced neutralizing antibodies -- which doctors say could protect against novel coronavirus infections -- in all of the trial's participants. 

Now what

Although Six Flags, SeaWorld, and Cedar Fair have all gone to great lengths to increase the safety of their guests -- such as implementing social distancing measures and new cleaning regimens at their parks -- it likely won't be enough to return their business to previous levels.

However, an effective vaccine for COVID-19 could go a long way toward helping amusement parks return to their former splendor. Although much more testing is needed, Moderna's vaccine progress could be an important step on the path to recovery.