Top coronavirus vaccine maker Moderna (MRNA -0.15%) used to be one of the stock market's stars. The company soared more than 400% in 2020 after bringing its vaccine from drawing board to market in less than a year.

But recent times have been tough for the biotech company. Sure, Moderna continues to bring in billions of dollars in vaccine revenue. But investors worry about what will happen to revenue in a post-pandemic world. As a result, the shares have dropped 52% this year. Worries may be overdone. That's because there's one critical thing about Moderna the market is ignoring.

The path so far

First, let's take a step back and look at what Moderna's done so far. The company emerged as a vaccine leader right from the start. Moderna and rival Pfizer have vaccinated most of the U.S. population. They have also sold billions of dollars in vaccine doses to countries around the world.

Last year, Moderna reported $18.5 billion in vaccine sales. And this year, it forecasts about $21 billion. That's according to advance purchase agreements signed so far.

This major success brings up one big worry, though. Will vaccine revenue plunge once the pandemic is over? After all, the coronavirus vaccine and strain-specific booster are Moderna's only commercialized products right now. I've written a lot about how these products should continue to bring in significant revenue -- even if it declines from today's level.

But here's the one critical point the market has ignored: Moderna is more than a coronavirus vaccine company. The vaccine offered Moderna a huge stepping stone into the world of commercialization. But this is just the beginning for this messenger RNA expert.

Moderna's pipeline includes 46 programs in development. And most of them aren't in the area of coronavirus prevention. In fact, the next three products closest to commercialization are investigational vaccines for the flu, respiratory syncytial virus (RSV), and cytomegalovirus (CMV).

Product launches in two to three years

These vaccines are all involved in phase 3 trials right now. And Moderna says the flu and RSV candidates could result in commercial launches within the coming two to three years. These products both hold blockbuster potential.

Today's flu market is worth $5 billion to $6 billion. And there are plenty of rivals out there. But Moderna aims to produce a more efficacious vaccine. That could demand a higher price and win over more individuals.

As for RSV, a vaccine currently doesn't exist, and the market for RSV vaccines in the older adult population could top $10 billion. If Moderna gets to the finish line first or even among the first, this could be big.

These are just Moderna's closest-to-market candidates. The company has many other compelling projects in preclinical development all the way through phase 2. If even a few of these candidates make it to commercialization, Moderna could have a very bright future ahead.

What does this mean for investors?

Right now, the market is focused on the potential loss of coronavirus vaccine revenue. That's weighing on Moderna shares. Today, they're trading at less than five times forward earnings estimates. That looks like a steal considering Moderna's long-term prospects -- well beyond the coronavirus program.

I don't expect the shares to rebound right away. Moderna is almost a victim of its success. When investors think "Moderna," they think "coronavirus vaccine stock." And then they start to worry about future revenue.

It may take a while for Moderna to show the world that it's a lot more than a coronavirus vaccine stock, and that its other potential products can lead to blockbuster revenue and growth over the long term.

But that's OK. This offers long-term investors an opportunity to buy this innovative biotech player for a bargain today -- and reap the rewards once Moderna's other programs begin to gain momentum.