What happened

Shares of Inovio Pharmaceuticals (INO -6.21%) are skyrocketing today, up by 32.6% as of 11:17 a.m. EDT, after surging as much as 48.9% earlier in the session. The biotech didn't announce any news. However, investors appear to be jumping back into the stock after Inovio's share price cratered 35% yesterday in the wake of a tweet by short-seller Citron Research.

Citron's tweet stated the U.S. Securities and Exchange Commission (SEC) should halt trading of Inovio stock and launch an investigation into the "ludicrous and dangerous claim that they designed a vaccine in 3 hours." The short-seller predicted that Inovio's share price would fall to $2, adding that "investors have been warned."

Coronavirus vaccine bottles

Image source: Getty Images.

So what

Investors buying Inovio stock today are probably aware that the SEC doesn't make decisions based on the tweets of short-sellers. The underlying factor driving Inovio's shares up by more than 130% year to date is the biotech's progress with its experimental vaccine for the novel coronavirus disease COVID-19.

Inovio announced on March 3 that it's accelerating the timeline for advancing its INO-4800 vaccine to an early-stage clinical study in humans. That study is expected to begin in April. Inovio also said that it plans to produce 1 million doses of the vaccine by the end of 2020.

There's no guarantee that Inovio's clinical study evaluating INO-4800 will be successful. But it's also too early to dismiss the company's chances. Inovio has previous experience in developing vaccines for viruses, including MERS, a member of the coronavirus family.

Now what

We'll have to wait and see whether Inovio's COVID-19 vaccine shows promise in early clinical testing. But while the biotech stock's near-term fortunes rest on how well this testing goes, Inovio does have other irons in the fire. Most importantly, the company expects to announce results later this year from a late-stage study of VGX-3100 in treating cervical high-grade squamous intraepithelial lesions (HSIL) caused by human papillomavirus (HPV).