What happened

Shares of Planet Fitness (PLNT -0.44%) leapt 9.6% on Wednesday, following hopeful coronavirus-related developments.

So what

Gyms have been hit hard by COVID-19. Many were forced to close during the pandemic. Even as some begin to reopen, many people are choosing to exercise in the comfort and safety of their own homes, rather than at gyms where they could be exposed to the novel coronavirus.

Women exercising at a fitness class.

Planet Fitness stock rose sharply on Wednesday. Image source: Getty Images.

Yet on Tuesday, investors received news that Moderna's experimental COVID-19 vaccine helped to produce neutralizing antibodies -- which researchers believe could help to stave off coronavirus infections -- in 100% of its phase 1 study participants. Though more trials are needed to show if the vaccine is truly effective against COVID-19, the news was a welcome relief to gyms and their members.

Now what 

With membership plans as low as $10 per month, many people may choose to keep their Planet Fitness memberships during the pandemic, even if they're not currently going to its gyms. However, if Planet Fitness is to continue to grow its membership count, an effective vaccine or treatment for COVID-19 will likely be required. Although still early in the clinical trial process, Moderna's announcement is a positive step in that direction.