When I think of a revolutionary stock, I think of companies with game-changing technology. They are handling problems in a new way -- or treating previously difficult-to-treat illnesses.

When should you get in on these players? It depends on your risk tolerance. If you're cautious, aim for a company that's already commercialized its technology. If you're aggressive, you might opt for an earlier-stage company.

Here, I'll talk about both: two clinical-stage players and one company that's generating billion-dollar revenue and profit from its innovations. They're stocks I'd buy right now without hesitation.

1. Vaxart

Vaxart (VXRT -3.67%) is working on a coronavirus vaccine candidate. But Vaxart's potential product is an oral one -- a pill to be taken with a glass of water. This formulation makes it revolutionary for patients and healthcare providers. Patients avoid a needle stick. And it's much easier for providers to transport and store a room-temperature-stable pill than a traditional vaccine.

Recently, Vaxart said its omicron-specific candidate and its original candidate both protected against the variant in preclinical tests. The original candidate is in phase 2 studies right now. The company expects to report initial data in the third quarter.

Of course, even if Vaxart is successful, the company will make it to market much later than bigger rivals. That said, a vaccine in pill form could easily gain market share at any point if it's safe and effective. And Vaxart doesn't depend uniquely on the coronavirus program. The company also is developing oral vaccine candidates for four other viruses, including flu and norovirus.

Vaxart is a good bet for aggressive investors -- especially considering its price has dropped more than 44% this year. Cautious investors may want to wait until this innovative company gets a bit closer to the finish line, though.

2. CRISPR Therapeutics

Speaking of the finish line, CRISPR Therapeutics (CRSP -0.88%) is getting very close to a big victory. The company and partner Vertex Pharmaceuticals have reported positive data on CTX001, their gene-editing candidate for blood disorders. And the two companies aim to file for regulatory approval by the end of this year.

This is big for a couple of reasons. First, it would represent CRISPR's first commercialized gene-editing product. And that would translate into product revenue. Second, the treatment could be a blockbuster. That's because as of now, treatment options are limited for blood disorders like sickle-cell disease and beta thalassemia.

And CTX001 is even better than the idea of a medication taken regularly. That's because it's designed as a one-time curative treatment. So, clearly, if this candidate reaches the market, it will be revolutionary.

CRISPR shares have climbed 46% from a low reached on May 9. So investors already may be anticipating a potential CTX001 approval. Still, the shares are down 16% since the start of the year. An approval and revenue down the road could keep the share gains going. Aggressive investors may want to get in on this story now -- and cautious investors might want to watch it closely.

3. Intuitive Surgical

Intuitive Surgical (ISRG 1.62%) is a great bet for both cautious and aggressive investors. The company is the leader in the global robotic surgery market. It holds nearly an 80% share, according to BIS Research. And Intuitive has shown it can grow revenue and profit -- into the billions -- over time.

There are a couple of reasons why this strength is likely to continue. First, Intuitive doesn't only generate revenue from the sales or leasing of its flagship Da Vinci robot. It actually makes more money from the sales of accessories and instruments. And it generates revenue from service packages to maintain its robots. So, it can count on a constant stream of revenue from those who have invested in the Da Vinci.

Second, Intuitive probably will remain a favorite of hospitals and surgeons. Hospitals are unlikely to switch to another system after making a million-dollar investment. And most surgeons train on the Da Vinci. That means they know the system well -- and probably would want to stick with it.

Intuitive's shares have struggled as the pandemic weighed on earnings. A wave of coronavirus patients often leads hospitals to postpone nonessential surgeries. So today, Intuitive is trading at 41 times forward earnings estimates. That's down from more than 70 in January. And that's a deal, considering today's troubles are temporary -- and the long-term outlook remains bright.