Why COVID-19 vaccines need to be stored in cold temperatures

The most difficult stage of implementing the initial COVID-19 vaccines – in fact, creating and testing them – occurs in less than a year after the coronavirus pandemic began, the fastest achievement in history.

“Nobody in the vaccine field, if you had asked them in March, would have said, ‘Yes, we will have a vaccine by the end of December,'” said Kawsar Talaat, MD, infectious disease physician and vaccine researcher, and professor assistant in the Department of International Health at Johns Hopkins University. “The fact that we were able to test and evaluate the vaccines, and that they proved to be incredibly effective, is really incredible.”

However, we are still not clear: sending and storing vaccines is a huge and expensive challenge. The vaccines from Moderna and Pfizer-BioNTech, which have received emergency use authorization from the Food and Drug Administration, must be kept below freezing temperatures until they reach their destinations, a technical obstacle that can hinder immunization efforts. While Americans eagerly await the chance to receive both doses, the country’s public health system is putting together a very cold distribution plan.

First, COVID-19 vaccines must be stored in cold temperatures.

The two approved COVID-19 vaccines require very low temperatures to remain viable, but this is not uncommon. According to the Pan American Health Organization, an international specialized health agency for the Americas, most vaccines are stored between -58 ° F and 46 ° F – but both options are at the bottom end of the scale.

The Pfizer vaccine must be stored and shipped at a shocking temperature of -94 ° F to remain effective. Moderna’s vaccine, however, should be stored at -4 ° F. If these temperatures are not maintained in all phases of the cold chain, certain elements may degrade, leaving the vaccine useless. Only in the final stage of the journey, when they are thawed to perform immunizations, can vaccines come out of this deep freeze.

The Modern vaccine can be stored for up to 30 days in normal refrigerator conditions; the Pfizer vaccine, up to five days. Both have a shelf-life of up to six months, so doses do not need to be used immediately, provided they are stored properly.

Their storage temperatures are probably very different due to the development and manufacturing processes, says Dr. Talaat, but as their formulations are particular, there is no way of knowing for sure.

Why do COVID-19 vaccines need to be kept so cool?

The frozen storage temperatures are a result of the mRNA technology of both vaccines. Any vaccine of this type is relatively fragile, explains Dr. Talaat, which means that they should be kept at lower temperatures. Overheat them and their potency (or the vaccines themselves) can degrade.

“When we create biological substances, we want to prevent anything from happening to them, so we often put them at very low temperatures to keep them stable,” she says. “It helps them stay [effective] as long as possible. “

When vaccines are developed, they undergo stability tests – basically, taking them out of the freezer and checking that they are resisting well. Lower storage temperatures generally mean greater stability, at least in the beginning, explains Dr. Talaat. To store them at higher (but still cold) temperatures, researchers prove that vaccines remain effective at the new temperature or add certain stabilizers to their list of ingredients.

None of the COVID-19 vaccines has been around long enough for complete stability tests, resulting in more convenient temperatures. “You want to make sure it works before you get there,” says Dr. Talaat. Because experts worked so hard to release these vaccines quickly, they didn’t necessarily have time to see what could keep vaccines stable at higher temperatures. (After all, more than 300,000 Americans died of COVID-19 this year.)

Now that researchers have the benefit of time, future generations of the vaccine are likely to be much easier to store; some COVID-19 vaccines already in development do not require such freezing to survive. The next generation of vaccines, including AstraZeneca, which is kept at normal refrigerator temperatures, already offers a glimpse of hope for easier storage.

How will storage temperature requirements affect the initial vaccine distribution?

The types of freezers that can keep current COVID-19 vaccines stable, especially those from Pfizer, are expensive and generally found only in hospitals and laboratories. “A clinic, a nursing home or even [regional] health departments may not have freezers that support -94 ° F, ”says Dr. Talaat.

Transport and storage are two of the biggest obstacles to the implementation of immunization worldwide. A Reuters report last month called complex vaccine requirements “an obstacle for even the most sophisticated hospitals in the United States.” Rural health service providers with few resources, with no resources to improve their cold storage, face even greater obstacles.

Since Moderna’s vaccine holds up well in normal freezers, Pfizer’s subzero option will be the most difficult to ship. The company is currently shipping its vaccine in so-called “pizza trays”, which contain 195 vials that remain stable for a few weeks, thanks to a constant supply of dry ice.

At the moment, Pfizer’s vaccine is being stored at the company’s production facilities and on “freezing farms”, huge storage facilities equipped with specialized freezers the size of refrigerators. (Interestingly, one of the only companies that produce freezers that reach these low temperatures is Dippin ‘Dots, which ships and stores its exclusive ice cream at -40 ° F.)

Modern vaccine bottles are still difficult to ship, but have caused less headaches so far. “You go from special freezers that only laboratories and hospitals have to freezers that any clinic will have,” explains Dr. Talaat. Both vaccines are already being distributed to government officials, health professionals and nursing home residents.

Even with such demanding storage, experts are breathing relieved because distribution is finally underway. “I am very happy to have a vaccine, even when it is stored [so low], which is 95% effective and can hopefully lessen this horrible pandemic, instead of waiting for one that is stable in the refrigerator, but having to wait longer, ”says Dr. Talaat. “I am very happy that these vaccines are available.”

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