Upstart Moderna is taking on an outsized role in the US vaccination efforts.

Pfizer did not ultimately receive government funding for research and development, although Warp Speed ​​provided $ 1.95 billion in July to secure 100 million shots, a deal that the government also said would support mass production.

Moderna’s late-stage clinical trial was slightly smaller than Pfizer’s, with 30,000 participants instead of the competitor’s 44,000. Both shots are about 95 percent effective for the general population, although Pfizer’s was more effective for adults over the age of 65, with 94 percent to 86 percent from Moderna.

But that may not be a statistically significant difference, said Steven Joffe, a University of Pennsylvania health policy expert and member of the Data Safety Monitoring Board. oversee several vaccine trials under the auspices of Operation Warp Speed.

“She and most of the other companies, with the exception of Pfizer, had a lot of help from the government and Warp Speed,” said Joffe, adding that Moderna’s success “is a great achievement.”

Moderna executives said at the FDA advisory committee meeting Thursday they saw no serious allergic reactions in the process; two incidents, one in the placebo group, were found to be unrelated to the injection itself. The data comes as US and UK regulators are working to better understand serious reactions to the Pfizer vaccine in people with severe allergies. Those reactions took place outside of clinical studies, which rarely include people with severe allergies.

The FDA panel voted 20-0 to recommend the vaccine, while Michael Kurilla, a scientist from the National Institutes of Health, abstained, saying he was “very uncomfortable” with a blanket recommendation for people older than 18 years old. Because of the severity of the pandemic and limited supplies, “I would prefer it to be more focused on people at high risk of more threatening illness and disease,” he said.

Moderna’s vaccine has several logistical advantages over Pfizer’s. Unlike Pfizer, Moderna chose to have the U.S. government split its shot, turning one of the biggest challenges of the vaccine push over to military personnel and commercial distributors led by General Gustave Perna, Warp Speed’s Chief Operating Officer.

Moderna’s shot can also be kept in most regular freezers, while Pfizer needs ultra-cold freezers or containers filled with dry ice that make shipping and storing that vaccine more challenging.

With FDA approval expected on Friday, the company faces its largest test to date. Warp Speed ​​officials say more than 4 million doses are ready to be shipped to the states by Monday, and the rest of the country’s 200 million dose orders will arrive in the next six months.

“I’m sure they have good people there, but this is their first product,” Loss said. “Every time you do something for the first time, there is a chance of mistakes, uncertainty.”