It may be a bit early to establish Moderna's (MRNA 1.33%) and Teladoc Health's (TDOC -0.46%) lasting growth stock status by looking at the past couple of years. Both have been through extraordinary times. Moderna launched the coronavirus vaccine as its first product in 2020 -- and vaccinated a good share of the population. Teladoc saw revenue and virtual medical visits soar in the triple digits as people opted to stick close to home.

As a result, Moderna went from zero product revenue to billions of dollars in a matter of months. And Teladoc's revenue crossed the $1 billion mark for the first time ever. Moderna's and Teladoc's situations were temporary. But that doesn't mean we shouldn't bet on them for more growth in the coming months or years. Both are on the right path. Which one is the better stock to buy now? Let's find out.

The case for Moderna

Moderna reported a whopping $18.5 billion in coronavirus vaccine revenue last year. And the company expects even more this year -- at least $21 billion, according to advance purchase agreements.

Moderna says the U.S. coronavirus vaccine market could be worth as much as $13 billion once the pandemic shifts to endemic. The company hasn't said anything about international sales yet. So, opportunity could be greater.

It's very possible Moderna's coronavirus vaccine revenue will settle at a lower level than it is today. But here's why that isn't a problem. First, vaccine revenue is likely to become recurrent. This will show investors Moderna's vaccine isn't just a pandemic product, but can drive revenue over time.

Second, Moderna's revenue has now given it the cash it needs to advance its pipeline. The company reported $18 billion in cash at the end of the second quarter. And right now, Moderna has three non-coronavirus candidates in phase 3 trials -- investigational vaccines for cytomegalovirus, respiratory syncytial virus (RSV), and flu.

Moderna has suggested that, if all goes well, the flu and RSV candidates could reach commercialization within the coming three years. RSV for older adults represents a market of more than $10 billion. And the flu market could expand beyond today's $5 billion to $6 billion size with the arrival of more sophisticated vaccines, Moderna says.

All of this means Moderna's growth opportunities may just be getting started. That's why, trading at less than five times forward earnings estimates, Moderna looks cheap.

The case for Teladoc

Teladoc's gains in revenue and virtual visits may have slowed from early pandemic days. But they're still climbing in the double digits. For example, in the second quarter, revenue and visits climbed 18% and 31%, respectively. And Teladoc predicts more than 20% revenue growth this year.

It's also important to remember that Teladoc's revenue was already on the rise before the pandemic. So telemedicine isn't just a pandemic trend. It's here to stay. In fact, at a compound annual growth rate of 25.5%, the global telemedicine market may reach more than $396 billion by 2027, according to Fortune Business Insights. 

Teladoc is a leading player. It offers services to more than half of Fortune 500 companies. And Teladoc said during its quarterly earnings report that its number of multi-million-dollar contracts in the pipeline is double what it was in the year-earlier period.

Teladoc disappointed investors this year with two billion-dollar non-cash goodwill impairment charges. This suggests it paid too much when it acquired Livongo in 2020. Livongo brought Teladoc additional strengths in chronic conditions management.

Over time, it's still possible for this purchase to bring value to Teladoc. Chronic care could be a key area. About 30% of Teladoc's chronic care members sign up for multiple programs. And the availability of multiple programs has shown that it can boost member retention rates. So this represents a key growth driver over time.

And it's important to note that Teladoc has steadily increased two key measures -- the number of U.S. members and revenue per member -- from quarter to quarter over the past year.

As for valuation, Teladoc is trading at about two times sales. That's its cheapest ever.

Moderna or Teladoc?

It's clear Moderna and Teladoc both have a lot more growth to come. They both also look cheap considering revenue prospects down the road.

But if I had to choose just one to add to my portfolio right now, I'd go for Moderna. The company is already profitable -- and that's set to continue. (Teladoc hasn't yet reached profitability.) Moderna also has at least two potential revenue and share performance catalysts in the next few years. I'm talking about possible regulatory approval of its RSV and flu vaccine candidates.

So, right now could be just the right moment to get in on the Moderna growth story.