Key Points Pfizer's vaccine candidate showed more than 90% efficacy, while Moderna's efficacy was 94.5%. Both companies continue to collect trial data, so figures may change in the coming weeks and months. Moderna says its investigational vaccine may be stored in standard refrigerator temperatures for 30 days. Our experts issued a rare "Double Down" Buy alert on this one stock... Learn more. Pfizer (NYSE: PFE) wowed the world last week when it reported positive interim efficacy data from phase 3 trials of its coronavirus vaccine candidate. In the days that followed, everyone talked about the potential Pfizer vaccine -- and wondered when and how they could get it. The European Commission even finalized an order for the future product after months of discussions. And Pfizer became the leader in the coronavirus vaccine race. But fast-moving footfalls weren't far off. Biotech Moderna (NASDAQ: MRNA) this week announced positive efficacy data from its own late-stage trial. The next steps for both players: reporting two months of follow-up safety data from the trials, then applying for Emergency Use Authorization (EUA) from the U.S. Food and Drug Administration. Right now, it may look like the companies are neck and neck. But in fact, Moderna has sprinted ahead. Here are two reasons why: Image source: Getty Images. 1. A strong and detailed efficacy report Both companies reported encouraging efficacy results. But Moderna's were the strongest -- and the most detailed. Pfizer said its vaccine showed more than 90% efficacy in preventing COVID-19. The company tested its vaccine in more than 43,500 participants, and this initial analysis involved 94 confirmed cases of the virus. Pfizer didn't offer further performance details. In the initial analysis of Moderna's phase 3 study, the vaccine candidate demonstrated efficacy of 94.5%. The study enrolled more than 30,000 participants, and this first look included 95 confirmed cases of COVID-19. Five of the cases were in the vaccinated group, and 90 of the cases were in the placebo group. Of the cases, 11 were severe -- and all of those occurred in the placebo group. And finally, 15 of the total cases occurred in adults age 65 and older. Moderna's overall efficacy figure surpassed Pfizer's. And the details offer us a glimpse of an important element: performance in older adults. The elderly have been among the most vulnerable to the coronavirus, so efficacy and safety in this group is essential. About 15% of the COVID-19 cases occurred in older trial participants. So Moderna is on the right path when it comes to vaccine performance in this group. Pfizer didn't provide information regarding efficacy in various age groups. Considering all of these elements, it's fair to say Moderna has slipped ahead of Pfizer from an efficacy standpoint. Still, when looking at data from Pfizer and Moderna, it's important to keep one thing in mind: These results may change in the coming weeks and months as more follow-up data become available. More cases of COVID-19 in the placebo groups could strengthen these companies' results -- and more cases in the vaccinated groups could weaken them. 2. A warmer temperature When we think of vaccines, we think about efficacy and safety. But the success of a vaccine doesn't stop there. Other behind-the-scenes factors can literally make or break a product's future. One of those is storage temperature. And this happens to be a weak point for Pfizer's investigational vaccine, which requires an ultra-low storage temperature -- negative 94 degrees Fahrenheit. That makes storage a challenge and an expense. Most vaccines only need standard refrigerator temperatures of 35 degrees Fahrenheit to 46 degrees Fahrenheit. Pfizer developed special shipping containers that use dry ice to help with transport of its vaccine. And healthcare facilities would need to consider buying special freezers to store it. This is where Moderna truly leaps ahead of Pfizer. The former company said this week that its vaccine candidate may be stored at refrigerator temperatures of 36 degrees Fahrenheit to 46 degrees Fahrenheit for 30 days. And it may even be left at room temperature for as long as 12 hours. For shipping and long-term storage, the vaccine requires a temperature of negative 4 degrees Fahrenheit. Pharmaceutical distribution companies routinely ship products at this temperature. So, what does this mean for both vaccine candidates? Even if Moderna's data are a bit stronger, both Moderna and Pfizer may win EUAs. Worldwide need for a vaccine means there is room for more than one provider -- as long as regulators are satisfied with efficacy and safety results. But when it comes to determining which company will take the largest market share, the temperature issue will be a decisive factor. And that factor pushes Moderna a step ahead. 10 stocks we like better than Moderna INCWhen investing geniuses David and Tom Gardner have a stock tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* David and Tom just revealed what they believe are the ten best stocks for investors to buy right now... and Moderna INC wasn't one of them! That's right -- they think these 10 stocks are even better buys. See the 10 stocks *Stock Advisor returns as of October 20, 2020 Adria Cimino has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.Source