Companies that developed one of several coronavirus vaccines say they're confident it works, after seeing good results in a trial. But if that vaccine is OK'd for mass use, it will take a huge effort to distribute it.

The Pfizer vaccine made headlines this week after the company and German partner BioNTech SE announced in a press release that the vaccine was 90% effective in a trial.

Some health experts are keeping optimism in check until they see more detailed scientific data, and the vaccine hasn't yet received FDA authorization to roll out to the public. But the news of success sent Pfizer's stock price up as the nation looks ahead to how a vaccine would be distributed.

Among the challenges? Pfizer's vaccine must be kept around -94 degrees Fahrenheit, requiring a level of "ultra cold" storage not typical of other vaccines. Once removed from the super-cold temperatures, the vaccines only last a few days in normal refrigeration.

Officials are confident local health systems have enough freezer space to store the first phase of the vaccine, which will be in limited supply and administered first to nursing home residents and health care workers.

NBC10's Mitch Blacher reports Philly is purchasing and installing two ultra-cold freezers (in a location undisclosed for security reasons). Each freezer will be able to hold about 160,000 doses of the Pfizer vaccine in the packaging the city will receive. The city paid a little over $19,000 including shipping for the freezers.

Meanwhile, the Centers for Disease Control and Prevention has told Pennsylvania not to purchase additional freezer storage, a state health department spokesperson told NBC10.

“At this time, the CDC has advised states not to purchase additional storage,” the spokesperson said in an email. “...We will be working to ensure that if the EUA-approved vaccines are those that require ultra-cold storage, that we have all we need to ensure we can get Pennsylvanians vaccinated.”

If Pfizer's vaccine is the standard going forward, hospitals and governments might need to bulk up their cold storage. The federal plan to roll out the vaccine goes in phases according to need.

"If we don’t have other alternatives by phases 2, 3...I have a feeling everybody is going to be scrambling to get a -80 freezer,” said Dr. Tony Reed, chief medical officer at Temple Health.

The Pfizer vaccine is most effective when patients get two doses three weeks apart. So health systems and governments will need to stay in touch with people receiving the vaccine and make sure they get their second dose at the right time.

"We need to track who we’ve vaccinated and when, we need to make sure they’ve showed up," Reed said.

Like other health systems, Temple is ready to store and distribute the vaccine if it's ready as quickly as some predict. In a news conference Tuesday, Philadelphia Health Commissioner Dr. Thomas Farley said the first Pfizer doses could be ready by December and administered to vulnerable populations and health care workers in the early months of 2021.

Reed said Temple Health already has some ultra-cold freezers used for research, though his team was looking into a purchase just for the pharmaceutical setting — to store the vaccine doses.

He remains interested in the trials for other companies' vaccines, which don't have as sensitive of storage requirements. According to CNBC, Moderna's vaccine must be stored at minus 4 degrees Fahrenheit. One from Johnson & Johnson can be stored closer to room temperature, Reed said.

Whether one vaccine is easier to handle than the other, Reed said decisions wouldn't be made solely based on a vaccine's ease of storage or logistics. "It’s not about one being better than the other. It’s about what’s the right drug" for the patient and the public, he said.

Farley said it’s still unclear how quickly the companies can scale up their production of the vaccines.

“So it may be several months before the vaccine is available to everyone here in Philadelphia. And unfortunately, much of the current surge of the virus in Philadelphia will happen before the vaccine arrives.”

Temple vaccine trial

Temple Health is one of the test sites for a vaccine trial underway with J&J Janssen. The company told Temple to find about 1,000 to 1,500 people for the trial, Reed said.

There has been no shortage of volunteers, whether they're motivated by doing good for their community, contributing to science, or getting a chance to receive the antibodies before the general public.

"We’re scheduled out for the next couple weeks, there is a long line of people, even when the vaccine was on pause. The community response has been tremendous," Reed said.

Good sign for other vaccines?

The news about Pfizer's vaccine trial made Philly's Dr. Farley optimistic about the other vaccines in the works. The Pfizer vaccine appears to have succeeded while only targeting one part of the virus: the spikes that form up its namesake corona.

"If this vaccine works, we would expect the other vaccines to work also. Here’s why: the Pfizer vaccine is a very narrowly targeted vaccine. It produces antibodies only to what is called the spike protein of the virus. This is the part of the virus that allows the virus to attach to human cells. So that’s an important target for a vaccine, but we didn’t know for sure that would be enough... The other vaccines that are being developed often have produced antibodies to the spike protein and other parts of the virus. So if the spike protein antibodies by themselves protect people, then these other vaccines should be protective as well."

NBC10's Mitch Blacher and Matt DeLucia contributed to this report.