Moderna (MRNA 0.17%) has taken center stage in the race to develop a coronavirus vaccine. In March, the clinical-stage biotech company became the first to bring a vaccine into human trials. Since then, management has reported encouraging trial data that allowed it to move on to phase 3 studies -- a final and crucial step before regulatory approval. Since the start of the year, the shares have surged by 297%.

Some investors may wonder if, considering the share gains, there is any steam left. Of course, it's impossible to guarantee a repeat performance of the stock's January-through-July increase. But with the world's attention focused on coronavirus vaccine makers, further gains by Moderna and others are possible.

Blocks spelling "buy" sit in an investor's hand.

Image source: Getty Images.

Here are three reasons to buy Moderna shares now.

1. Phase 3 just started

Moderna launched its phase 3 trial July 27. The study will test the vaccine candidate on as many as 30,000 participants across 100 sites. The company hopes to enroll volunteers who are at high risk for contracting COVID-19 -- healthcare workers, for example. The primary endpoint is the prevention of symptomatic COVID-19. Secondary endpoints include the prevention of severe forms of the illness and prevention of infection whether symptoms are present or not.

With the late-stage trial beginning, statistics give us reason to be optimistic. The overall probability of success for infectious disease vaccines in clinical trials is 33.4%, according to research published in Biostatistics last year. That's the highest probability of success among all therapeutic groups. Still, failure can come at any moment during the clinical trials process, so we should remain vigilant.

Any positive data from Moderna's phase 3 study or further reports from earlier trials is likely to drive the shares higher in the coming months. And a possible commercialization would surely keep the momentum going.

2. Government funding

Here's another reason to be positive about Moderna's vaccine candidate: The U.S. government chose the company as one to support as part of its initiative to help bring a vaccine to market by January 2020. Operation Warp Speed initially awarded Moderna up to $483 million to cover development through regulatory approval. The government in late July increased its total award to $955 million to fund an expansion of phase 3 testing to 30,000 volunteers. Moderna originally aimed to enroll fewer participants.

Operation Warp Speed has offered funding to other companies, including AstraZeneca (AZN -0.18%), Johnson & Johnson (JNJ 0.23%), and Novavax (NVAX -9.65%). Still, this is a small group considering there are 25 companies or research institutes investigating candidates in human studies.

Government funding doesn't mean Moderna's vaccine will succeed or that the government will select it as a vaccine of choice for Americans. But it does mean Moderna has the funds needed to take its candidate all the way through the development process.

3. Today's price

The current price can't be considered a bargain. Moderna doesn't yet have products on the market, and it's too soon to say whether the coronavirus vaccine will win regulatory approval. Still, Moderna's stock price has dropped 18% since the record high it reached in mid-July. For investors looking for an entry point, this may be it. In fact, the stock may stagnate a bit or even extend recent declines amid a lull in news flow as the phase 3 trial gets going. The next major catalyst likely will be further trial data.

So there you have it: Three reasons to buy Moderna shares. This doesn't mean Moderna is a buy for every investor, though. It may be the right choice for biotech investors with a strong appetite for risk, but others may be better off watching from the sidelines. Successful clinical trials might equal more gains, but a possible late-stage failure could be devastating.