Kathryn Stephenson, MD, MPH (Center for Virology & Vaccine Research, BIDMC) discusses COVID-19 vaccine distribution and the complications that hospitals may face with the need for ultra-cold freezers to store the vaccine.

Slate – November 13, 2020

Pfizer’s COVID Vaccine Has to Be Stored at -80°C. There’s Already a Run on Freezers.

Dry ice will also be crucial to keeping the vaccine cold. Leon Neal/Getty Images

There are a few caveats to the promising news this week about one of the coronavirus vaccines being developed. For one thing, it has to be kept cold during distribution. Very, very cold.

On Monday, Pfizer announced that its coronavirus vaccine proved to be 90 percent effective based on early analysis of the data from a clinical trial involving 44,000 people. In a press release, the pharmaceutical giant said that the vaccine, which is administered in two doses, provides protection for at least a month, though further testing could reveal that the effects last longer. Pfizer is planning to apply for an emergency use authorization, a special certificate for emergency situations, from the Food and Drug Administration at the end of November, which is when the company will have enough safety data to make such a request. Dr. Anthony Fauci has said that the vaccine could be available to high-priority populations in December, and to the general public in April.

Pfizer’s vaccine takes advantage of a genetic material called mRNA, which enters cells and induces the production of certain proteins. The mRNA in this particular vaccine helps cells to produce the spike proteins that jut out from the surface of the virus. When a body’s immune system encounters the spike proteins that the vaccine helped to create, it learns how to recognize and fight the virus. This mRNA needs to be kept at an extremely cold temperature—minus 80 degrees C storage—or else it will spoil. “At warm temperatures it comes apart, dissolves itself, becomes useless,” said Georges Benjamin, executive director of the American Public Health Association. “Just like if you had a piece of food out on the table for too long, or if you put ice cream out in hot weather.” The coronavirus vaccine isn’t the only one that needs to be kept so cold; for example, the Ebola vaccine has to be stored at minus 60 degrees C to minus 80 degrees C.

Because of the odds that a COVID vaccine will need to be distributed at very low temperatures—Moderna’s vaccine, for example, also involves mRNA—hospitals and health systems around the country have been snatching up freezers that are capable of storing the vaccine, as well as dry ice for shipping. Such freezers are typically found at research facilities, rather than run-of-the-mill doctor’s offices or retail pharmacies. Storage at minus 80 degrees C “is very tough for resource-poor settings, and it’s actually tough for a lot of regular clinics in most communities,” Kathryn Stephenson, a professor at Harvard Medical School who directs the clinical trials unit for virology and vaccine research at the Beth Israel Deaconess Medical Center, told me in an interview Monday. Major health systems in Maryland, California, North Dakota, North Carolina, Ohio, Pennsylvania, Kansas, and Michigan have told news outlets in recent days that they’re either leasing or purchasing units. The federal government doesn’t seem to have a nationwide plan for distributing freezers, so states have largely been left to figure it out themselves. It’s unclear how many of these freezers are in the U.S., but there are efforts to produce more, as experts expect there to be a shortage. There are fewer than 10 national suppliers of the freezers, and manufacturing a unit can take anywhere from 10 days to six weeks. Manufacturers have been trying to hastily assemble a freezer supply chain that can handle the demand since at least September.

Transporting the vaccines at such a cold temperature will also pose some logistical challenges. Pfizer plans to ship the vaccine in containers that can hold 1,000 to 5,000 doses, reports Stat News. The containers have slots for dry ice that can keep the vaccines at the appropriate temperature for 10 days, and then for another 15 days once opened, assuming you replace the dry ice every five days. The vaccines can then survive an additional five days at refrigerator temperature. These temperature constraints don’t leave a lot of room for transportation delays, though shipping companies have been building infrastructure to accommodate the vaccine. For instance, UPS has been constructing freezer farms in Kentucky and the Netherlands with units that can hold up to 48,000 vials each, which the company can use as stopover points during distribution. Given all that, shipping the vaccines across the country shouldn’t be as much of a concern as ensuring that local clinics and pharmacies have access to the right equipment to store them.

The freezers, which cost between $10,000 and $20,000, are likely to be too expensive for rural hospitals that are already operating at a loss, which threatens to exacerbate preexisting inequalities in the health care system. Such hospitals often serve elderly, low-income populations that will be in dire need of the vaccine. “I’m hoping that the federal government will step up to the plate and offer resources,” said Benjamin. “They’re going to have to have some federal assistance either through a reimbursement mechanism or through some kind of capital support.” Areas with unreliable electrical networks will also need to plan for possible power outages, which could cause vaccine inventories to spoil.

The Pfizer vaccine is only one of many that are currently in development. Other vaccine types can be stored at higher temperatures. For instance, the COVID vaccines that Johnson & Johnson and AstraZeneca are working on can survive in a standard refrigerator. Because of this, the Centers for Disease Control and Prevention has actually been advising state health departments against purchasing ultracold freezers. “One of the things that people are hoping for is that one of the other vaccines will be able to be stored just in your refrigerator, because those of course would be much easier to transport and get out to rural clinics,” Stephenson said.

Yet there’s a lot we still don’t know about these other vaccines. There could be a scenario in which a company develops a vaccine that can survive in a regular refrigerator, but which has harsh side effects or an efficacy rate far below the 90 percent that Pfizer is currently reporting. If multiple vaccines eventually get the go-ahead from the FDA, Benjamin predicts that there will be a debate over the trade-offs of each option, and storage temperature will surely be a factor. “When we had the polio vaccine, we really ended up having two different vaccines and the nation went through a debate for some time over which vaccine was safer and easier to deliver,” he said. “Some [coronavirus] vaccine may come along that tops them all. [A vaccine] that takes only one shot and can be kept in a regular refrigerator is the ideal situation, but we don’t have that yet.”