There's leftover COVID-19 vaccine. So what do you do with it?

With COVID-19 vaccines having strict timelines for when they must be used before expiring, including some that must be used within hours of being mixed and thawed, having leftover doses may be somewhat inevitable.

So what happens in those cases? Who receives the doses and how do people find out where leftover shots are available?

Although there's no nation-wide data tracking wasted vaccine doses, it's likely that only a small fraction of distributed vaccine doses must be thrown away.

Still, this small fraction may amount to many thousands of doses -- and advocates say that it's crucial, in a time of limited supply and facing the specter of spreading variants, to get as many shots in arms as soon as possible.

According to a North Carolina Department of Health and Human Services (NCDHHS) report obtained by ABC station WTVD, 2,346 doses of the COVID-19 vaccine were marked unusable and thrown out in North Carolina.

And Texas issued a report on March 5 indicating that some 6,800 doses had been discarded out of 7.6 million -- about 0.09%. The state has administered some 6.7 million doses overall, according to its vaccination dashboard. Doses were discarded for a number of reasons, including that their expiration date had passed or inadequate refrigeration.

Some doses are wasted because of human error in mixing, preparation or transportation. But many doses are discarded when people don't show up to vaccine appointments, leaving extra shots on hand with a quickly dwindling expiration date.

Now, some local communities are crowdsourcing solutions. Some of those solutions are low-tech, like putting up a flyer at a grocery store notifying shoppers of extra vaccine doses.

Still, others rely on social media and the internet to give local residents a heads up about extra doses that would otherwise go to waste. Among those high-tech solutions are websites like Dr. B, VaccineHunter, and countless Facebook groups that have cropped up since the start of the vaccine rollout.

'Fantastic idea'

After struggling to help his mom get vaccinated by searching pharmacy websites, Doug Ward, a 25-year-old entrepreneur, created VaccineHunter.org to help address the issue in his community. Ward says he does not accept donations or payment for the services.

“I stumbled upon …. a page called New Orleans vaccine hunters. So I was like, wow, this is a fantastic idea. Why not do the same thing here in Colorado? So I started a vaccine hunter group in Colorado. And I was like, why stop there?” Ward told ABC News.

The website connects users with a Facebook group in their area where people can share information about excess vaccines and their availability. Currently, the site hosts more than 46 groups in 34 states with over 253,000 members.

“I saw a problem and a point where I think I could make a little Band-Aid solution to make everyone better off and help people. So that's exactly what I did,” Ward said

The issue of leftover vaccines and what is done with them has been controversial. Vaccines are prioritized by age group, co-morbidities, profession, and other factors in an attempt to get them to those who need them most first.

Gray area

When it comes to a handful of leftover vaccines set to expire soon, some pharmacists and doctors might allocate on a first-come-first-serve basis -- a decision that at times has been controversial.

In December, Dr. Hasan Gokal was fired from his job as medical director of Harris County Public Health Department in Texas for giving away 10 doses of the Moderna vaccine that were going to expire. He was charged with theft by a public servant and accused of breaking county protocols by the district attorney, but the charges were later dropped.

"In the absence of having any other options, I contacted people who I thought would be eligible or would know somebody who would be eligible," Gokal said in an interview on "The View."

States and the Centers for Disease Control and Prevention (CDC) have started issuing guidance urging leftover vaccines not be wasted. The CDC has recommended rolling over unused vaccine into the next week's allocation (some doses are good for a couple of weeks at refrigerated temperatures, for instance). This guidance did not exist when Gokal was fired in December.

“I really think that's really tragic that he lost his job for giving out the excess vaccine. I do think it was very new at the time… he was one of the kinds of pioneers of giving out excess vaccines,” Ward said.

The CDC has partnered with Vaccinefinder.org to help people find local vaccine providers and availability and is frequently updated -- although this database does not specifically pair people with leftover vaccines.

The CDC has partnered with Boston Children’s Hospital to create Vaccinefinder.org, a website that helps people find local vaccine providers and availability and is updated daily. Although this database does not specifically pair people with leftover vaccines, the website provides real-time visibility into vaccine inventory, which can help make sure appointments are filled and reduce overall waste.

Not 'skipping the line'

Ward said he developed his site to address what he says is the lack of a unified vaccine rollout plan.

“I was really hoping we would see a nationalized system to distribute excess vaccines and vaccines in general…in Colorado, we don't have a state system, you have to go into a CVS website…Meanwhile, in New Mexico, they have a state-run system that will notify if there's any,” Ward says.

Colorado's vaccine website links users to the pharmacies that distribute the vaccine to set up an appointment, rather than a state coordinated effort.

Ward said that he believes that those who don't fall into priority groups receiving leftover vaccine “isn’t skipping the line.”

"It's kind of how like how you won’t have all the seats filled on a ride and someone comes from the single rider line," he said. "Whenever there's these kinds of gaps in availability, you want to kind of push them in there and make sure that you have that ride full at all times, you're not wasting any vaccine."