The Covid-19 vaccine co-developed by Pfizer and BioNTech has been available in the U.S. since December, when the FDA granted emergency use authorization to the two-shot regimen. Now the partners are seeking full FDA approval.

Emergency use authorization is temporary status that lasts for the duration of an emergency. Formal FDA approval would permit the companies to market the vaccine in the U.S. It would also provide additional validation for the messenger RNA vaccine, potentially persuading those who have been hesitant to get vaccinated. So far, 170 million doses have been doses have been distributed in the U.S., according to the companies.

Pfizer and BioNTech said Friday that they filed their application to the FDA under a rolling review, which means completed sections of the application will be submitted as they become available rather than all at once. This type of review gives the FDA the option to review portions of the application before the submission is complete. Pfizer and BioNTech said they started the application by filing with the regulator nonclinical and clinical data for the vaccine in those 16 and older. The remaining pieces include manufacturing and facility data. Those submissions will be made in coming weeks.

Modena, maker of the other FDA authorized mRNA Covid vaccines, said in its release of first quarter financial results that it plans to start a rolling application with the FDA later this month.

Once the FDA receives all parts of an application, it will set a target date for a regulatory decision. Standard review is 10 months. Pfizer and BioNTech said they plan to seek priority review, which would shave four months off that timeline. But a regulatory decision might not take that long. Safety and efficacy for the vaccines were established in the clinical trial data that supported emergency use authorization. The FDA had already required efficacy data from a Phase 3 study, and safety data from Phases 1 and 2 with the expectation that at least half of the recipients in the Phase 3 study had at least two months of follow-up.

In early April, Pfizer and BioNTech reported the latest data from Phase 3 tests showing that their vaccine was 91.3% effective against the novel coronavirus up to six months after the second dose. In terms of preventing severe disease, the vaccine was 100% effective. The vaccine’s safety was also upheld at the six-month mark. The companies said that the submission for full approval includes this six-month post vaccination data.

Pfizer and BioNTech last month formally asked the FDA to expansion the emergency authorization of their vaccine to include children 12 to 15. The request follows the report of clinical data in late March showing the vaccine led to 100% efficacy in that age group. The companies said they plan to seeking approval for the vaccine in this age group once clinical data become available for patients six months after the second dose.

The regulatory progress for Pfizer and BioNTech comes amid calls for vaccine makers to waive patent protections for Covid vaccines so that others may step in and manufacture more of these products to ensure equitable distribution worldwide. Last week, the Biden administration said it would support waiving of patents.

In a letter to employees that was also circulated on social media, Pfizer CEO Albert Bourla said the lack of manufacturing infrastructure is not the reason vaccines are not more widely available. The limitation, he said, is the availability of the raw materials used in vaccine production.

“The proposed waiver for COVID-19 vaccines, threatens to disrupt the flow of raw materials,” Bourla said. “It will unleash a scramble for the critical inputs we require in order to make a safe and effective vaccine. Entities with little or no experience in manufacturing vaccines are likely to chase the very raw materials we require to scale our production, putting the safety and security of all at risk.”

As of May 3, Pfizer and BioNTech say they have distributed about 430 million doses of their Covid vaccine to 91 countries and territories around the world.

Photo by Christian Charisius – Pool, via Getty Images