Thanks to its globally in-demand coronavirus vaccine, Moderna (NASDAQ:MRNA) is one of the hottest companies on the market right now. And with the pandemic continuing worldwide despite the slow distribution of effective vaccines, it's safe to say that its product will be lucrative for quite some time.

But does that make Moderna's stock a buy for new investors? Or has the market already priced in the expectation that the company's revenue will continue to soar as its manufacturing capabilities scale up and allow it to access more and more of the global coronavirus vaccination market? In my view, Moderna will probably continue to outperform, but there's a solid chance that its growth could soon either slow down -- or potentially accelerate.

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Why you should buy it now

The argument in favor of buying Moderna today is that its future revenue from vaccine sales will likely be even larger than today's. 

The company is still signing brand-new sales agreements for millions of doses of vaccine, as it did with Argentina on July 12. And management is still pursuing upgrades to its global production capacity, as shown by the commissioning of a contract manufacturing site in France earlier this month. 

In the first quarter of 2021, Moderna made $1.73 billion from deliveries of 102 million doses of the vaccine. More than $19.2 billion in pre-purchase agreements have already been signed for this year. By the end of 2022, it expects to make as many as 3 billion doses, which is a big step up from the maximum of 1 billion doses that it has scheduled for 2021. In short, the coronavirus vaccine is a money printing machine, and for the moment, there doesn't appear to be any sign that it will stop.

And that's before taking the prospect of booster shots into account. Moderna seems to be expecting that additional doses will be needed for fully vaccinated people, perhaps as routinely as every six months. That would massively increase the demand for doses, and it'd be a huge boon to the company's shareholders and new investors. But government regulators in the U.S. seem to disagree with management about the need for booster shots, which could be problematic.

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Why it might be better to wait for clarity on the booster issue

Cautious investors may want to avoid buying Moderna until there's a consensus about whether booster shots will be needed. As of right now, the U.S. Food and Drug Administration (FDA) and the Centers for Disease Control (CDC) concur that coronavirus booster shots won't be necessary to preserve immunity. That puts Moderna and other vaccine manufacturers like Pfizer at odds with the official position. 

At the moment, it's unclear whether the market has fully priced into Moderna's valuation the future sales of booster shots. If it hasn't, regulators can double down on their "no boosters needed" stance, and it won't threaten the stock price very much, as it doesn't imply any major revenue changes from what's expected. 

On the other hand, if investors are counting on booster shots to justify the stock's current price, there's a chance of experiencing losses for people who buy now, assuming that the CDC and the FDA stay firm. There's no way to tell in advance whether regulators will change their minds, so the only way to avoid the risk is to stay clear of the stock. 

New shareholders may need to wait for big returns

As frustrating as the uncertainty surrounding booster doses may be for potential investors, it shouldn't dissuade anyone from purchasing the stock today. 

There's a lot more to Moderna than the coronavirus vaccine alone, and soon enough it'll be bagging revenue from other successful programs. Some of these projects, like its seasonal influenza vaccine currently in phase 1/2 clinical trials, have the potential to be massively profitable. Even if investors need to wait several years before other vaccines make it through the approval process, there's the certainty of oodles of coronavirus vaccine revenue between now and then.

So, as long as you're planning on holding Moderna for the long term, it's a good purchase right now.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.