Key Points

  • Pfizer's vaccine candidate showed it was more than 95% effective, 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.

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Pfizer (PFE -0.19%) 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 (MRNA 0.89%) this week announced positive efficacy data from its own late-stage trial. The next steps for both players: 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's one reason why:

A researcher vaccinates a clinical trial participant with a coronavirus vaccine candidate.

Image source: Getty Images.

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? 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.