Moderna (MRNA -2.45%) shares soared 20% in one trading session on Monday after the company reported positive interim data from its coronavirus vaccine clinical trial. The data is indeed promising -- across all participants in two dosage groups, levels of binding antibodies were at or above levels seen in people who have recovered from the virus. Binding antibodies attach themselves to a pathogen, but they don't stop infection. That's where neutralizing antibodies come in -- and data on that, as well as results from a larger patient group, may be key for Moderna's vaccine, and, as a result, for the company's share price performance.

Moderna might be considered the leader in the coronavirus vaccine race. The clinical-stage biotech company was the first to bring a vaccine candidate into human studies when it began trials in March. The rapidity may be thanks to Moderna's technology. The company doesn't use the traditional vaccination method of introducing a weakened or dead version of the virus into the body. Instead, Moderna's coronavirus vaccine -- like its other investigational products -- uses messenger RNA to give the body's cells instructions to make proteins that would prevent (or in some cases treat) disease.

The gloved hand of a researcher holds a coronavirus vaccine.

Image source: Getty Images.

What we know so far

So let's get back to neutralizing antibodies and what we know so far. Moderna's data came from a phase 1 trial involving 45 healthy adults. They were split into three groups according to dosage level, and the vaccine was given in two doses. The study evaluates safety, side effects, and immune response.

Moderna's report this week offered immune response data after two doses for two of the dosing groups -- the 25-microgram and 100-microgram groups. Though information on binding antibodies was available, information on neutralizing antibodies was limited, with results available for only the first four participants in both of those dosing groups -- a total of eight people. In those participants, neutralizing antibodies were at or above the levels seen in recovered coronavirus patients. While binding antibodies signal a problem to the body's immune cells, which then take on the threat, neutralizing antibodies themselves are able to stop infection.

Moderna's neutralizing-antibody data is encouraging, but with results concerning only eight people, it's much too soon to draw conclusions. And even if these results eventually apply to all 45 trial participants, it still won't be enough to determine the vaccine's success or failure. To put this into perspective, consider that the Centers for Disease Control and Prevention has shown that thousands of people are involved in clinical testing before a vaccine is brought to market..

That said, we shouldn't be discouraged if neutralizing antibodies come in lower in one of the dosage groups, as this ongoing phase 1 trial will report more results in the coming weeks. Moderna is in the process of testing dosage levels, so one group might produce better results than another.

Neutralizing antibody data

At this point, investors should plan on monitoring neutralizing antibody data through Moderna's later-stage trials, as those will involve more participants. Moderna aims to enroll 600 healthy adults in its phase 2 study. And a phase 3 study -- Moderna expects to start one in July -- typically involves thousands of participants.

Any positive clinical trial news may lift Moderna's shares in the coming weeks as the world seeks a solution to the coronavirus pandemic. The Trump administration recently announced Operation Warp Speed, an initiative to accelerate the development of a coronavirus vaccine with a goal of bringing one to market by January.

Meanwhile, for Moderna, a positive result on neutralizing antibodies in a larger group of people might boost shares, as it would be a sign that the vaccine may work. That, along with the government's will to bring a vaccine to market quickly, may strengthen Moderna's position as a leader in the race to develop a coronavirus vaccine.