Moderna (MRNA -2.21%) is at a crucial moment right now -- for its COVID-19 vaccine candidate, its pipeline as a whole, and its investors. The company's investigational vaccine for COVID-19 is entering phase 3 clinical trials this month. This is the key stage that could make or break the company's hopes of bringing the product to market. And for investors, the results may mean an enormous gain -- or big losses.

Is the chance of success greater than the chance of failure? Let's take a look at what Moderna has reported so far, as well as possible risks ahead.

Vials labeled COVID-19 Vaccine are set on top of $100 bills.

Image source: Getty Images.

Moderna is a clinical-stage company, meaning it doesn't yet have products on the market. The biotech company has about 20 candidates in the pipeline for indications including autoimmune disorders, cancer, and infectious diseases. A lot is riding on a possible COVID-19 vaccine approval because it would give Moderna a commercialized product.

And one more important point: Moderna's entire pipeline -- including this vaccine -- is based on the same technology, so positive data here may boost investor confidence in the rest of the company's work. Moderna uses messenger RNA (mRNA) to deliver instructions to the body's cells. These instructions tell the body to make certain proteins that can prevent or treat disease.

Encouraging interim data

So far, Moderna's news has been positive. The company reported encouraging interim data from phase 1, with trial participants showing levels of binding antibodies and neutralizing antibodies at the same levels as or above those of recovered COVID-19 patients. Binding antibodies are those that alert the body to the presence of a pathogen, but more importantly, neutralizing antibodies actually block infection.

Though Moderna is moving in the right direction, the vaccine must prove itself in a few areas. In the interim report, data on neutralizing antibodies was only available for eight trial participants. We must see this trend in many more before declaring victory.

Another missing piece has to do with the age of trial participants. The interim data concerned volunteers age 18 to 55. Moderna currently is treating older groups in phase 2. This age group is extremely important for any successful vaccine because elderly patients have been among the most vulnerable during the COVID-19 pandemic. It's essential that a vaccine works for them.

And finally, in phase 3, Moderna faces the challenge of showing efficacy in a study group of about 30,000 participants.

Operation Warp Speed

Moderna's vaccine success also depends on the U.S. government and other companies in this vaccine race. Through Operation Warp Speed, the U.S. government vowed to help bring a vaccine to the people by January. The Department of Health and Human Services has awarded as nearly $500 million to Moderna and $1.2 billion to AstraZeneca. The two companies are close leaders in the race, with AstraZeneca's vaccine candidate now in a phase 2/3 trial.

With the great global need for a vaccine, there is room for more than one company on the podium. But it's clear Moderna's best share performance will happen either if its vaccine reaches the finish line first or if its vaccine is better than that of rivals.

Moderna soared as much as 309% this year to its peak in May. The stock then pulled back when company executives sold shares after releasing trial data. But these sales were actually set up in advance -- prior to knowledge of what the trials might bring. Moderna shares are now up 215%. Wall Street predicts the stock could gain as much as 49% from here, according to the average estimate.

Could Moderna shares make you a millionaire?

In the near term, everything will depend on the results of the COVID-19 vaccine's clinical trials. As we've seen, the shares are sensitive to good and bad news on the subject.

So far, I'm encouraged by trial data. But considering the strong link between this development program and Moderna's share price, I'll wait to see more data on neutralizing antibodies and the vaccine's results in older trial participants -- and whether AstraZeneca takes a clear lead or falls behind -- before I'll call Moderna a millionaire-maker.