Most biotech companies are too risky to even think about holding forever. Between the big risk of a clinical trial blowing up and the lesser risk of getting one-upped by a competitor's medicine even after successfully moving a drug from the lab to the market, it's incredibly difficult to feel confident in a biotech's long-term future.

There are, however, a couple of exceptions to that trend. Let's take a look at two that are ready for a purchase and long-term hold today.

Medical professionals discussing data on a laptop in a conference room.

Image source: Getty Images.

1. Moderna

Moderna (MRNA -1.11%) is a biotech stock that needs no introduction after successfully commercializing its coronavirus vaccine and raking in $18.8 billion in revenue in 2022 as a result. At this point in the game, most investors who are familiar with the company probably recognize that it's intending to be the industry's leader in messenger RNA (mRNA) medicines.

Given that mRNA medicine is an emerging field that's only in the very early phases of its market expansion, Moderna may well succeed in its goal, and even if it doesn't, it'll still almost certainly be a star for many years to come. Here's why.

Right now, the business has 48 programs in its pipeline, 15 of which are therapeutic vaccines that are intended to treat various cancers, rare diseases, and cardiovascular disorders. Separately, it has four programs in phase 3 clinical trials, and nine programs in phase 2 trials. That means it can fail to commercialize 75% of its mid- to late-stage projects and still enjoy a handful of the surviving candidates making it to the market. In biotech, those are good odds, and it's unlikely Moderna will actually fail that much at all. 

So why buy Moderna right now? Its valuation is so low that the stock is selling for peanuts, and the bargain will likely be fleeting. Its price-to-earnings (P/E) ratio is 6.7, which is shockingly small in contrast with the biotech industry's average P/E of 23.1. The fact that the coronavirus jab heyday is over is what's causing the market to value its shares so cheaply. Estimates calling for its revenue to plunge this year and next year are probably correct as management's sales projections are for only $2 billion for the first half of 2023.

But the falling sales of the near term will eventually give way to more new medicines getting commercialized, and growth will return once again. And when it does, shareholders will be getting wealthier, perhaps for decades if Moderna manages to maintain the current pace and breadth of development in its pipeline.

2. Maravai LifeSciences

Maravai LifeSciences (MRVI 3.95%) is a biotech that's upstream of Moderna. It sells the nucleic acids that Moderna and other mRNA drug developers like BioNTech and Pfizer need to do research, conduct clinical trials, and manufacture doses of their mRNA medicines. That means if its customers are going to go big on their mRNA pipelines over the next decade -- and they are -- Maravai stands to make a ton of money along the way whether its customers succeed in commercializing new drugs or not.

Therefore, Maravai is a bit of a safer pick than Moderna, but it's also likely to grow a bit less, especially in the near term when the need for its precursor chemicals to make coronavirus shots is anticipated to fall sharply.

In 2022, Maravai brought in revenue of $883 million, and while management hasn't provided a sales guidance figure for 2023, Wall Street is estimating that it'll only make $431 million. But those analysts also see its top line returning to growth in 2024. It might not dip again after that if demand from its biotech collaborators continues increasing as more mRNA programs move into clinical-stage development. 

The reason to buy Maravai stock right now is the same as for Moderna. With a P/E multiple of about 8, its valuation is so low that it's hard to pass up given its strong long-term prospects as a principal supplier to mRNA companies.

In terms of the risks associated with an investment, Maravai is largely exposed to the general level of hype regarding mRNA products. If its customers strike out with clinical trials one too many times, it's likely that the market will lose some faith in its total addressable market. Nonetheless, with so many different candidates in development, and more doubtlessly on the way, that risk is minimal for the moment.

And if the mRNA field turns out to be what its evangelists are hoping for -- and based on the favorable and growing body of scientific literature about mRNA medicines right now, it might -- Maravai's shareholders will be stacking returns, perhaps for decades to come.