Some might say Teladoc Health (NYSE:TDOC) was in the right place at the right time last year. As the coronavirus pandemic worsened, medical offices closed or operated at lower capacity. And as stay-at-home orders broadened, many people decided a trip to the doctor's office wasn't such a good idea anyway. Enter Teladoc, a platform for online medical visits.

As you can imagine, Teladoc's already growing services grew even more -- and so did its share price. Teladoc stock climbed 139% last year. Now, the question is whether this 2020 winner can continue that pace in 2021. There's more to Teladoc's success than the "right place, right time" idea. Here are three reasons why I think this healthcare stock still has potential in the new year.

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1. The telemedicine market is expanding -- even without the pandemic

Teladoc offers virtual visits in more than 450 medical subspecialties, and its services are available in more than 175 countries. The company has about 51.5 million members. Sure, the coronavirus provided a huge boost last year, but Teladoc's revenue was already on the rise prior to the outbreak. Since 2005, Teladoc has conducted more than 15 million virtual visits -- the most of any player in the industry. Annual revenue has climbed since the company went public in 2015.

TDOC Revenue (Annual) Chart

TDOC Revenue (Annual) data by YCharts

Another sign that virtual visits are a lasting trend: Last year, in areas where doctors' offices reopened and returned to pre-coronavirus capacity, Teladoc visit volumes still grew. In fact, they grew at more than double their pre-coronavirus rate.

And finally, the global telemedicine market, at a compound annual growth rate of more than 22% since 2015, reached about $49.9 billion in 2019, according to The Business Research Company.

2. The coronavirus crisis isn't over

Those numbers give us a "without the pandemic" picture. Now let's add the pandemic to the mix. The U.S. and other countries have started to vaccinate citizens. But that doesn't mean the coronavirus health crisis will come to an end overnight. There aren't enough doses to vaccinate everyone in a short period of time. And there are some people who don't want a vaccine or who can't be vaccinated for health-related reasons.

Meanwhile, U.S. coronavirus cases are on the rise. And this means people who might have otherwise made a physical medical appointment may opt for a virtual visit from home. So Teladoc's double and triple-digit revenue gains, as seen in the second and third quarters, respectively, probably aren't over. And let's return to The Business Research Company report I mentioned above. It predicts that the global telemedicine market, at a growth rate of 40%, will reach more than $194 billion in 2023.

3. The Livongo merger will add to growth

Teladoc recently completed a merger with Livongo. Some investors frowned on the $18.5 billion deal, preferring Teladoc go it alone. (The announcement of the deal sent the shares down 19% in one trading session.) But from a long-term perspective, I think the merger of these companies was a good idea.

Livongo specializes in the digital management of chronic conditions such as diabetes and hypertension. And business has been booming. Second-quarter revenue soared 125% year over year. And membership in the company's diabetes management program climbed 113% to more than 410,000 members.

Together, Teladoc predicts the companies will deliver an 85% increase in 2020 pro forma revenue to $1.3 billion. The deal will grow revenue and, at the same time, reduce costs over time. Teladoc is forecasting cost synergies of $60 million by the end of 2022. Those savings will be used to further grow sales and expand margins, Teladoc says.

Though Teladoc is a leader in telemedicine and the market is growing, it's still important to consider the competitive landscape. Rivals are present and gaining strength, from smaller player Amwell (NYSE:AMWL), which went public in the fall, to online retail giant Amazon (NASDAQ:AMZN). For now, Amazon's telemedicine program is for employees only. But if that changes, it's more than likely to steal some market share from other players. And that's another reason why it was wise of Teladoc to team up with fellow high-growth company Livongo.

Teladoc's share gain last year doesn't mean performance is over. It may have just begun. The alliance with Livongo and revenue growth prospects -- with or without the coronavirus pandemic -- make me optimistic about this stock's future.

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.