The COVID-19 pandemic is responsible for most of the uncertainty facing investors right now. Even though the Nasdaq Composite (NASDAQINDEX:^IXIC) has gained ground during the global health crisis, large segments of the U.S. economy could remain under threat until a permanent solution to the coronavirus is developed and widely distributed.

Investors are therefore looking to pharmaceutical and biotech companies in hopes that one or more will provide the tools needed to beat the pandemic. On Wednesday morning, the Nasdaq Composite and Nasdaq-100 indexes both rose, largely because of favorable news from Moderna (NASDAQ:MRNA) on the vaccine front. However, for every winner there are losers, and rival Inovio Pharmaceuticals (NASDAQ:INO) was among the morning's worst performers.

Why Moderna stock is on the rise

Shares of Moderna were up by as much as 11% Wednesday morning after the clinical-stage biotech announced the latest information from its phase 1 study of mRNA-1273, its SARS-CoV-2 vaccine candidate. Investors were pleased with the results, which confirmed earlier indications about mRNA-1273's potential.

Moderna published an interim analysis of its study, which involved giving patients two doses of mRNA-1273 four weeks apart in varying dosage amounts. According to the analysis, the vaccine didn't cause any serious adverse events through the first 57 days of the study, although several patients did report minor side effects like fatigue, chills, and pain at the injection site. The vaccine candidate resulted in considerable neutralizing activity, including antibody titers that were significantly higher than those in the control group of patients with confirmed diagnoses of COVID-19.

Side of building showing windows and a red and blue Moderna logo.

Image source: Moderna.

With these positive results in hand, Moderna is moving ahead with its plan to start a phase 3 trial of the vaccine candidate before the end of July. That advanced study will include 30,000 participants receiving doses of mRNA-1273, and will gauge how effective it is in preventing people from contracting COVID-19 or experiencing symptomatic cases of the illness. The researchers will also look at whether it reduces the chances of people who do get infected experiencing severe COVID-19 symptoms that require hospitalization.

Moderna is set to join the Nasdaq-100 Index, and Wednesday's gains will further justify its inclusion in that large-cap group. Shareholders are excited by the prospect that it could end up being first to come out with a viable vaccine to fight COVID-19 at a time when effective responses to it are desperately needed.

Bad news for rivals

What's good news for Moderna, however, wasn't good news for some of the other companies vying for position in the fight against COVID-19. Inovio's stock has also soared in 2020 due to its coronavirus efforts, but just now, the stage belongs to Moderna, and Inovio shareholders weren't celebrating as the stock was down by almost 9% as of 11:40 a.m. EST.

Many have seen Inovio as the frontrunner in the race to bring a viable coronavirus vaccine to market -- it has already delivered some encouraging early trial results for its candidate, INO-4800. Moreover, the company intends to move forward with phase 2/3 trials for INO-4800 this summer, putting it among the early group of those doing advanced-stage research.

However, this race doesn't necessarily have to have just one winner. Moderna and Inovio are taking different approaches to helping the human body protect itself against the COVID-19. Inovio's uses DNA plasmids to encourage cells to create defenses, while Moderna's uses messenger RNA. Researchers may eventually find that the best solution includes vaccines that use a combination of strategies to provide more complete protection. However, combination studies would have to be conducted to verify that even successful vaccines don't end up diminishing each other's effectiveness.

There's still a long way to go before Moderna, Inovio, or any other company will be able to declare victory over the coronavirus. That won't stop investors and traders from jumping the gun and sending stocks higher as those companies reveal more progress in their efforts.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.