What happened Shares of the clinical-stage biotech Inovio Pharmaceuticals (NASDAQ: INO) gained a respectable 10.9% over the course of May, according to data provided by S&P Global Market Intelligence. The DNA vaccine company's shares rallied last month on the news that its pan-COVID-19 vaccine candidate, INO-4802, showed strong signs of efficacy across multiple strains of the virus in preclinical studies. So what Despite being one of the first American biotech companies to develop a COVID-19 vaccine candidate last year, Inovio has fallen woefully behind the leaders in the space over the last year. In fact, there probably won't be a significant need for another vaccine in the U.S. by the time Inovio pushes its lead COVID-19 vaccine candidate, INO-4800, into late-stage testing this summer. Image source: Getty Images. A pan-COVID-19 vaccine, however, may still serve a purpose in the fight against this global pandemic. Investors, in turn, appear to be betting that the company may yet derive a relatively healthy revenue stream from its COVID-19 vaccine platform. Now what Is Inovio's stock worth buying after last month's double-digit uptick? Although the biotech exited the first quarter of 2021 with over $500 million in cash, Inovio's future remains murky at best. The company's lead product candidate, VGX-3100 for precancerous cervical dysplasia caused by high-risk HPV 16/18, needs a strong showing in its upcoming confirmatory phase 3 trial readout. What's more, there's no way to predict how the second-tier COVID-19 vaccine market will shape up over the next two years. In short, Inovio's stock doesn't sport a particularly compelling investing thesis as things stand now. 10 stocks we like better than Inovio PharmaceuticalsWhen investing geniuses David and Tom Gardner have a stock tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* David and Tom just revealed what they believe are the ten best stocks for investors to buy right now... and Inovio Pharmaceuticals wasn't one of them! That's right -- they think these 10 stocks are even better buys. See the 10 stocks *Stock Advisor returns as of May 11, 2021 George Budwell has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.Source