Moderna (MRNA -2.46%) stock already brought investors a 434% gain last year -- and it's heading for a 160% increase in 2021. That's after the biotech company became the second to commercialize a coronavirus vaccine -- and claimed the title of market leader along with Pfizer. Moderna's first-ever product also has made a big impact when it comes to earnings. The vaccine is generating billions of dollars in revenue and profit every quarter.

As we look back on that stock market success story, it's logical to wonder if we're reaching the last chapter. Sure, Moderna has been great. But for those who haven't yet invested in this biotech, is it too late? Or is there more to come for this vaccine giant in 2022?

A masked woman takes a selfie with her vaccine card.

Image source: Getty Images.

Cutting sales guidance

Moderna's latest earnings report sent a shiver through the market. That's because the company cut its guidance for vaccine sales this year. But as I wrote at the time, the reason had nothing to do with lower demand. Instead, it simply was a shift to deliver vaccines first to lower-income countries -- they pay less -- and defer some deliveries to higher-income countries -- they pay more -- to next year.

There aren't any clear signs that demand will drop anytime soon. Instead, there are signs it might continue. First, experts say the coronavirus will stick around post-pandemic. The regular emergence of variants supports this idea. The world was focused on the delta variant for months. Then, it almost seemed as if we could start thinking about the end of the pandemic. But in recent weeks, the omicron variant appeared.

Meanwhile, Moderna has won advance purchase agreements with various countries through 2023. And it even signed a supply agreement with Canada through 2024.

Right now, it's impossible to predict vaccine revenue levels in the coming years, however. That's because, even if demand continues, it isn't clear how pricing will evolve. Still, based on demand alone, it's likely revenue will remain significant.

Moderna already has brought booster candidates designed to handle multiple variants into clinical trials. And it's now developing one specifically to handle omicron as well. We don't yet know which candidate ultimately will be most useful. But Moderna has so many irons in the fire that it's likely one will be a winner. Especially considering Moderna's track record in the coronavirus vaccine race.

Not just a coronavirus company

But Moderna isn't just a coronavirus vaccine company. And this is probably the best reason to buy the stock today. The company has a rich pipeline of candidates -- all based on the same mRNA technology that powers the coronavirus vaccine. That doesn't mean every candidate will be successful. But knowing the method can work in humans is positive.

And another potential blockbuster may be around the corner. Moderna recently launched a phase 3 trial for its cytomegalovirus (CMV) vaccine candidate. CMV is a common virus that's particularly dangerous for unborn babies and people with weakened immune systems. Moderna predicts peak annual sales of $2 billion to $5 billion.

Other exciting programs in the Moderna pipeline include a potential HIV vaccine and a personalized cancer vaccine -- both of these could be gamechangers.

Now, let's take a look at Moderna's shares. They're down more than 40% from a high reached back in August. And at the current level, they're trading at only 10 times forward earnings estimates. That's down from as high as 18. And these earnings estimates don't include other potential products down the road.

Two important measures of financial strength are on the rise -- free cash flow and return on invested capital.

MRNA Free Cash Flow Chart

MRNA Free Cash Flow data by YCharts

So, let's get back to our original question: Is it too late to buy Moderna stock? If you're a long-term investor, it's not too late to buy shares of this dynamic biotech company today. The stock may not soar overnight. It might even stumble a bit over the uncertainty about future vaccine revenue -- as I mentioned above. But in the coming years, Moderna's coronavirus vaccine sales and sales of other potential products may prove that this biotech star has staying power.