(CNN) As a condition of the emergency use authorizations issued for the Pfizer/BioNTech and Moderna coronavirus vaccines, those companies are expected to work toward asking the US Food and Drug Administration for full approval -- and some health officials are hoping it will happen soon.
These vaccines have been in use since mid-December under emergency use authorizations, known as EUAs. During the pandemic, real-world data have shown the vaccines are effective against the coronavirus that causes Covid-19.
Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told CNN's Jim Sciutto on Wednesday he hopes Covid-19 vaccines will receive full FDA approval "very soon," and that the FDA will work "as expeditiously as possible" on approval applications for coronavirus vaccines as they come in.
Progressing from authorized to approved would allow manufacturers to market and directly distribute their vaccines. It could also have an impact on vaccine mandates -- and perhaps sway skeptics hesitant to get the vaccines now.
Currently, the three Covid-19 vaccines distributed in the United States -- made by Pfizer/BioNTech, Moderna and Johnson & Johnson -- are authorized, but not approved.
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. 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.
When the health emergency is over, "then any EUA(s) issued based on that declaration will no longer remain in effect," according to the FDA. So, vaccine makers will have to file a separate application for vaccines to be fully licensed.
CNN has contacted Pfizer/BioNTech, Moderna and Johnson & Johnson -- the most recent Covid-19 vaccine to be authorized -- about their plans to apply for full approval of their vaccines. None provided a timeline.
The typical approval process for vaccine developers requires completing lab research, pre-clinical testing and Phase 1, 2 and 3 clinical trials in humans. That has already been done for these coronavirus vaccines.
The FDA also requires vaccine manufacturers to submit data to support their manufacturing processes, facilities, product characterization and demonstration that the vaccine can be produced reliably and consistently.
Once all of that is complete -- both the clinical trials and manufacturing details -- companies can submit a Biologics License Application or BLA to the FDA.
"By submitting a BLA to the FDA, a company is seeking permission to distribute and market a vaccine for use in the United States," according to the FDA's website.
"FDA evaluates the data to determine whether the safety and effectiveness of the vaccine has been demonstrated and whether the manufacturing and facility information assure product quality and consistency. After its evaluation, FDA decides whether to approve (also known as to license) the vaccine for use in the United States."
Applications designated as "priority review" mean the FDA's goal is to take action on an application within six months. A "standard review" could take longer.
"When you're getting a formal approval you have to have a certain amount of time just observing predominantly the safety -- and obviously the safety looks really, really good in well over 140 million people having been vaccinated with at least a single dose," Fauci said on CNN on Wednesday.
After all, as spread of the virus is reduced, the nation may no longer be under an emergency situation and the vaccines will need a different type of green light under the FDA.
The agency is "the gold standard of a safety and regulatory organization throughout the world," said Fauci, chief medical adviser to President Biden. "I hope they do it quickly."
A concern around authorized-but-unapproved vaccines hinges on vaccine hesitancy.
If history is any indication, skepticism -- if not outright mistrust -- about an unapproved vaccine is nothing new.
One study published in 2009, months after the US declared a public health emergency due to the H1N1 influenza and the World Health Organization declared it a pandemic, researchers explored the public's willingness to use a drug or a vaccine with an EUA -- not full FDA approval -- by surveying a representative sample of more than 1,500 US adults.
The researchers, from the University of Pittsburgh and the University of Georgia, found that about 77% of respondents would be moderately, very or extremely worried if offered an unapproved vaccine; some 63% said they would not take it.
But the study also found that there were some other key factors that would convince respondents that a vaccine authorized under an EUA was safe to use.
If the vaccine were administered by a public health professional, 55% of respondents said they would take it.
If it came with a fact sheet, just over 57% of those surveyed said they would get it.
If their own health care provider administered the vaccine, that number shot up to 68%.
Dr. Jerome Adams, US surgeon general during the Trump administration, wrote in an opinion piece published in The Washington Post on Tuesday that approval will help show skeptics that the authorized coronavirus vaccines are safe.
"We should also pursue full Food and Drug Administration approval and expand covid vaccinations to youths," Adams wrote in part.
"The individuals who got vaccinated early on were generally high risk and willing to take a vaccine authorized for emergency use. But many people who are lower risk understandably ask if the benefits justify taking a medication that has not received the full and traditional FDA stamp of approval," he wrote. "As vaccine manufacturers complete further studies, which will eventually lead to expanded eligibility among minors, it will help show skeptics that the authorized covid vaccines are safe."
Some organizations say they expect to require the vaccine, but have opted not to while it's authorized and not yet fully approved.
"People, when they hear it's still emergency use, they still have a little concern about how far you can go with it," Fauci said on CNN Wednesday.
The University of California and California State University systems announced last week that their universities intend to require faculty, staff and students to be vaccinated against the coronavirus -- but the requirement would go into effect only once a vaccine has received full FDA approval. The proposed policy would begin this fall.
The California State University noted in its announcement, "This requirement will become effective at the beginning of the fall 2021 term, or upon full FDA approval of the vaccine, whichever occurs later."
President Joe Biden said in an exclusive interview on The Today Show, which aired Friday morning, that he wasn't sure whether Covid-19 vaccinations will be required for military members once the shots receive full approval from the US Food and Drug Administration.
"Once the FDA gives final approval for the vaccinations -- not emergency use authorization, but final approval -- will you order servicemembers to get the Covid vaccine?" NBC's Craig Melvin asked Biden during the interview.
"I don't know. I'm going to leave that to the military," Biden said.
"I'm not saying that I won't. I think you're going to see more and more of them getting it," Biden added. "It's going to be a tough call as to whether or not they should be required to have to get it in the military because you're in such close proximity with other military personnel, whether you're in quarters where you're all sleeping or whether you're out on maneuvers."
In early April, data provided to CNN indicated that nearly 40% of Marines are declining the Covid-19 vaccine. The Marine Corps is the first branch of the military to provide service-wide numbers on acceptance and declination.