Moderna (MRNA 3.38%) has brought plenty of early investors solid returns. The stock has soared more than 700% over the past two years. That's as the company developed its coronavirus vaccine and brought it to market.

If you haven't bought Moderna shares yet, you may be wondering if it's too late to buy this vaccine maker. Or is there still plenty of fuel left in the tank? Before making a decision, let's check out the following two charts.

An pensive investor sits in front of a laptop in a living room setting.

Image source: Getty Images.

2021 and 2022 revenue

The first chart shows the coronavirus vaccine revenue of Moderna and certain rivals this year and next year. Pfizer has generated the most coronavirus vaccine revenue so far, according to the data. The company's vaccine -- Comirnaty -- brought in $36 billion in revenue last year. And the expectation for next year is $29 billion, the chart shows. Moderna reported $18 billion in vaccine revenue for 2021. And revenue this year is expected to be even higher. The forecast is $22 billion, according to the chart.

This chart shows forecasted revenue for certain coronavirus vaccines.

Image source: Statista.

The trend for Moderna is looking even better than the trend for Pfizer. That's because Pfizer's vaccine revenue is forecast to decline this year from last year's level.

Investors have worried about a drop in revenue among vaccine companies as the world moves from pandemic toward an endemic situation. But the above chart shows Moderna's growth may be stronger than that of larger rival Pfizer.

Now, let's look a bit farther into the future. The following chart showing mRNA product revenue forecasts will help us out. It shows a significant decline in mRNA product revenues from 2021 to 2024. Revenue of about $50 billion last year is forecast to drop to $21 billion. This figure concerns all companies making mRNA products -- not just Moderna.

This chart shows forecasted revenue of mRNA products through 2035.

Image source: Statista.

A unique situation

This may be discouraging. But it shouldn't be. Here's why. The pandemic was kind of a unique situation. So, it's normal that it would create a massive opportunity for revenue. And this is giving Moderna the cash it needs to invest in the rest of its pipeline. If mRNA product revenues do indeed fall to levels on this chart, Moderna will make less from its vaccine than it does today. But that doesn't mean revenue will be low. It still could be at a blockbuster level.

And it's important to remember that Moderna has more than 44 programs in the pipeline. Two potential blockbusters -- vaccines for common viruses cytomegalovirus and respiratory syncytial virus -- have even moved into pivotal trials.

If a small number of these candidates are successful in the coming years, they can power revenue ahead. And that would remove Moderna's reliance on the coronavirus vaccine -- its only product at the moment. So, the first chart offers me optimism that Moderna's vaccine revenue growth may continue at least through this year. And the second chart tells me that mRNA product revenue potential down the road is strong -- even if it falls from today's extraordinary level. That makes Moderna a smart buy for the long-term investor.