Two of the major U.S. vaccine candidates undergoing final testing right now will need to be transported and stored in medical-grade deep freezers or cold ice, a factor that could complicate the dissemination of the vaccine.
"The only vaccines that require that kind of storage - very, very cold storage - are the RNA vaccines, that is, Pfizer and Moderna," explained Dr. David Agus, CBS News Medical Contributor and Professor of Medicine and Engineering at the University of Southern California.
Pfizer has developed its own cooler that will be delivered along with the vaccine in order to smooth out logistical issues.
But, said Dr. Agus: "Moderna will require the government to put large freezers in those places… that's going to be a major supply chain issue."
Pfizer and Moderna, along with Astra-Zeneca, are currently the furthest along in the vaccine development process, with Johnson & Johnson and other companies expected to take longer.
That could mean that distribution of the earliest available vaccines will be stymied or slowed by transport and storage issues.
Other vaccines in development are not RNA vaccines and therefore can be stored using more standard refrigeration.
