Coronavirus vaccine stocks were among the best performers on the market over the past couple of years. Novavax soared by 2,700% in 2020 on optimism about its COVID-19 program. Moderna (MRNA -2.21%) climbed by 1,200% and BioNTech gained more than 600% from the start of 2020 through the end of last year. Even pharma giant Pfizer rose 59% during that period.

If you missed out on those big gains, you should recognize that vaccine stocks probably won't repeat those stellar performances. But there are still plenty of investment opportunities out there in the world of healthcare -- especially if you plan to buy and hold shares for the long term. One of those strong opportunities just so happens to be a coronavirus vaccine stock -- today. But its next growth drivers may come from other indications.

A lot more to this well-known company

The company I'm talking about is none other than Moderna. We all think of its popular COVID-19 vaccine when we think of this innovative biotech player. That's natural -- the vaccine is its only commercialized product right now. But there's a whole lot more to Moderna.

The coronavirus vaccine has brought it two important things that may help it achieve lasting success. First, it has helped the biotech build up $19.3 billion in cash, and it continues to generate billions of dollars of earnings -- funds the company can use to advance its pipeline candidates and make acquisitions.

The vaccine also proved that therapies based on Moderna's mRNA technology work in humans. This is important because its entire pipeline is based on this technology. As Moderna President Stephen Hoge said on the most recent earnings call, "we believe our COVID vaccine success has derisked our vaccine pipeline." 

And speaking of the pipeline, that is precisely why Moderna is my best biotech stock to buy and hold right now. The company has 46 programs in development. Outside of its COVID-19 program, three of these are in late-stage development: vaccine candidates for cytomegalovirus (CMV), respiratory syncytial virus (RSV), and flu.

The respiratory candidates -- RSV and flu -- could launch within the next two to three years if all goes smoothly, Moderna has said.

First-to-market advantage

The market for flu vaccines is crowded. But there are no approved RSV and CMV vaccines, so those offer Moderna opportunities to grab the first-to-market advantage. If either earns regulatory approval (or if both do), the opportunities could be big. So I wouldn't expect Moderna to be a one-product company for long.

Moderna shares now trade for less than 6 times forward earnings estimates, down from 18 about a year ago.

Of course, it's possible revenue will decline from today's levels. Many people who received their initial inoculations against COVID-19 may not go for boosters every year. But even if demand for the vaccine declines, sales may remain significant. Large percentages of those populations at the highest risk probably will opt for boosters. And Moderna plans to charge more for its vaccine once it is selling directly to pharmacies and health care providers rather than to governments.

So if Moderna's vaccine revenue declines, it could do so gradually. Meanwhile, the company is advancing pipeline products that could soon make up for that lost coronavirus vaccine revenue.

The long-term picture

With so many programs in the pipeline, Moderna is preparing itself to be a multiproduct company over time.

For instance, the company has a combined coronavirus-flu vaccine candidate in preclinical studies. This could be a winning product of the future because it would be attractive to those who usually go for annual flu shots. Also in preclinical studies, Moderna is working with partner Vertex Pharmaceuticals on an inhaled candidate treatment for cystic fibrosis patients who can't be treated effectively with today's most effective drugs. And Moderna's personalized cancer vaccine candidate, which is in phase 2 trials, could be a game-changer.

All of this means that at today's price, Moderna's stock is a bargain. Its revenue story right now may be big -- but it's possible there will be a lot more to come. That's why it would be a great idea to buy the shares now and hold onto them for the long term.