It wasn't all that long ago that Moderna (MRNA -0.79%) ranked among the hottest stocks on the market. The company emerged as one of the top winners in the race to develop COVID-19 vaccines. Moderna's shares skyrocketed 2,500% from its initial public offering in December 2018 through July 2021.

But the story has been much different for Moderna since then. The glow from the early COVID-19 vaccine success quickly faded. What's next for the beaten-down vaccine stock? Here's what the smartest investors know about Moderna stock.

1. Significant uncertainty remains

Moderna's share price has been highly volatile so far this year. This isn't likely to change anytime soon for a simple reason: Significant uncertainty remains about the demand for COVID-19 vaccines. As a result, there's also significant uncertainty about Moderna's financial performance over the next few years.

Vaccination rates in the U.S. and in other countries appear to have flatlined for the most part. At the same time, the number of COVID-19 cases has declined. These two factors don't seem to bode well for Moderna and other coronavirus vaccine makers.

On the other hand, some experts think another COVID-19 wave could be on the way in the fall and winter. Moderna now has a booster targeting the coronavirus omicron variant. It's also developing a combination COVID-19/flu vaccine candidate. All of this could point to better days ahead for Moderna, perhaps as soon as early next year.

The smartest investors understand that there's no way to know for sure how the COVID-19 market dynamics will play out.

2. Don't rely on common valuation metrics

It makes sense to look at a stock's valuation before buying. Some like the price-to-earnings ratio. Others prefer valuation metrics based on enterprise value or free cash flow. But astute investors know not to rely on any of these common valuation metrics when it comes to Moderna.

To be sure, Moderna might seem like a bargain based on those metrics. For example, the stock trades below 3.7 times trailing-12-month earnings. The vaccine maker's enterprise-value-to-revenue multiple is only 1.8. Both are exceptionally low levels.

However, both are also potentially deceiving because of the big question marks hanging over Moderna's head. The company's revenue and earnings could fall significantly in 2023. Analysts are certainly predicting a steep decline. The consensus revenue forecast for Moderna in 2023 is a little under half the anticipated sales the company should generate this year. 

3. Future prospects go far beyond COVID-19

The smartest investors have a long-term perspective. And they will recognize that Moderna's future prospects go far beyond COVID-19. However, this critical point is something that the market seems to be largely ignoring.

Moderna's pipeline features three late-stage programs outside of its COVID-19 focus. The company is evaluating experimental vaccines targeting cytomegalovirus (CMV), respiratory syncytial virus (RSV) in older adults, and seasonal flu. Moderna thinks that results from its RSV and flu vaccine studies could be available next year. Its CMV data could be ready by 2025.

All three of these programs reflect big opportunities for Moderna. The global flu vaccine market currently stands at close to $6 billion per year. Moderna thinks the RSV market could top $10 billion annually. The CMV market is estimated to be between $2 billion and $5 billion. 

Moderna also has multiple programs in phase 1 and phase 2 testing. Personal cancer vaccine candidate mRNA-1457 especially stands out. Moderna is evaluating the experimental vaccine in phase 2 testing in combination with Merck's immunotherapy Keytruda in treating melanoma. Merck thinks highly enough of the potential for the combo that it recently exercised an option to jointly develop and commercialize mRNA-1457 with Moderna.

Messenger RNA (mRNA) technology offers tremendous flexibility in targeting many diseases with both vaccines and therapeutic drugs. Moderna remains one of the world's foremost leaders in mRNA. Investors in the know will appreciate that, despite the near-term uncertainty, the company's long-term future could be bright.