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Pfizer/BioNTech has initiated its application to the US Food and Drug Administration for full FDA approval of its Covid-19 vaccine for people ages 16 and older, the companies said Friday. This is the first Covid-19 vaccine in the United States to be assessed for full approval from the FDA.

Pfizer’s mRNA two-shot vaccine is currently being used in the US under emergency use authorization (EUA) from the FDA. The companies say 170 million doses of the vaccine have been distributed across the US to date.

“We are proud of the tremendous progress we’ve made since December in delivering vaccines to millions of Americans, in collaboration with the U.S. Government,” Albert Bourla, chairman and chief executive officer of Pfizer, said in a statement. “We look forward to working with the FDA to complete this rolling submission and support their review, with the goal of securing full regulatory approval of the vaccine in the coming months.”

To apply for full FDA approval Pfizer/BioNTech submitted a Biologics License Application, known as a BLA. The FDA requires vaccine manufacturers submit data on manufacturing processes, facilities and additional information that demonstrates that the vaccine can be produced reliably and consistently. They are also required to submit all pre-clinical and clinical trial data.

Pfizer/BioNTech will submit that information to the FDA over the next few weeks on a rolling basis. Once all the required information is submitted, a goal date will be set for a decision by the FDA. Pfizer/BioNTech has requested priority review, which asks the FDA to take action within 6 months, compared to the 10 months designated under standard review.

The application to the FDA is only intended for adults 16 and older. Pfizer/BioNTech is simultaneously applying to expand its EUA to include children ages 12 to 15. The companies then plan to submit an additional BLA to cover this younger age group once the essential data has been collected six months after administering second doses.

EUA vs. approval

The vaccine, named BNT162b2, was the first Covid-19 vaccine to be awarded FDA emergency use authorization in December.

Emergency use authorization is what its name suggests – a medical product, such as a vaccine, that gets special FDA authorization to be used during an emergency. For an EUA to be issued for a vaccine, the FDA says there must be adequate manufacturing information to ensure quality and consistency, and the known and potential benefits of the vaccine must outweigh its known and potential risks.

Due to the seriousness of the pandemic, vaccine makers originally applied for EUAs because the authorization process takes less time than what would be required for full approval. As a condition of the EUA, the companies were expected to work toward full approval from the FDA.

Progressing from authorization to approval could have an impact on vaccine mandates, as some organizations and schools have said they intend to require vaccination against Covid-19, but only once a vaccine is approved by the FDA. It could also have an impact on vaccine hesitancy; a Kaiser Family Foundation survey released this week says about 15% of American adults say they’ll “wait and see” to get a Covid-19 vaccine, and some cite the lack of full approval as a reason to delay.

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Clinical trials and recently published real-word data show the vaccine is up to 95% effective at preventing infection, severe illness and hospitalization. Pfizer/BioNTech reported last month that trial results show the vaccine remains more than 91% effective against disease with any symptoms for six months.

Recent research suggests the vaccine is effective against some worrying virus variants, and Pfizer/BioNtech is currently testing booster and variant-specific vaccines.

CNN’s Jacqueline Howard contributed to this report.