What happened

Moderna (NASDAQ:MRNA) shares soared 228.3% in the first half, according to data provided by S&P Global Market Intelligence, as the company advanced its COVID-19 vaccine through clinical studies and announced promising early data.

A researcher examines a vaccine dose in a lab.

Image source: Getty Images.

Moderna became the first company to begin clinical trials on a vaccine as the coronavirus spread throughout the world. The company's vaccine candidate entered a phase 1 study in March, then began phase 2 in May.

Interim phase 1 data showed that participants developed at least as many binding and neutralizing antibodies as recovered COVID-19 patients. Binding antibodies signal the presence of a pathogen, while neutralizing antibodies actually block infection.

So what

The coronavirus outbreak has resulted in more than 10 million cases so far and more than half a million fatalities, according to the World Health Organization. In the absence of an approved vaccine or treatment, the world is focused on drugmakers and vaccine makers that might develop one as soon as possible.

The U.S. government has even developed an initiative -- Operation Warp Speed -- to help bring a vaccine to market by January. As part of that program, the Department of Health and Human Services promised Moderna as much as $483 million in funding.

For Moderna, a clinical-stage company, regulatory approval would be positive in two ways: First, it would give the company its first commercialized product, and second, one approval may build investor confidence in the rest of Moderna's platform. The technology used to develop the potential vaccine for COVID-19 is the same technology used throughout Moderna's pipeline of potential products.

Now what

Moderna plans to begin a phase 3 trial on as many as 30,000 participants this month. Earlier-stage trials are ongoing. Though early results were encouraging, they dealt only with participants ages 18 to 55. Moderna now will have to show safety and efficacy in older patients. This is significant because the elderly have been among the most vulnerable during this health crisis.

Investors, and eventually regulators, also will be looking for more data on the participants' production of neutralizing antibodies. In the interim results, that information was available for only eight patients.

And finally, even though Moderna was the first to enter clinical trials, big pharmaceutical company AstraZeneca (NYSE:AZN) is emerging as another leader. AstraZeneca, collaborating with the University of Oxford, advanced a vaccine candidate into phase 2/3 trials.

If AstraZeneca becomes a clear leader and wins approval first, Moderna's big share gains might be over. But if Moderna produces solid trial results and makes it to the finish line first, or along with others, this biotech company's great share performance may continue.