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Vaccine Awareness

Understanding the Vaccine Cold Chain

It’s that requirement in order to maintain stability, they have to be maintained in a cold environment, like a refrigerator or freezer,” says Robert O. (Bill) Williams III, Ph.D., Johnson & Johnson centennial chair and professor and division head, Molecular Pharmaceutics and drug delivery at The University of Texas at Austin College of Pharmacy.

Moderna’s vaccine, which data shows is 94.5% effective, must be kept at -20°C, which is -4°F. That level of cool it’s comparable to a typical freezer.

Meanwhile, the vaccine by Pfizer and its partner BioNTech, which is shown by clinical trials to be 95% effective against COVID-19, must be kept at it even colder temperature: -70°C which is -94°F. That ultra-low cold chain is known as “the deep freeze.” Pfizer will ship thermal boxes of the vaccine vials packed with dry ice.



One of the major challenging is making sure refrigeration and freezers are accessible across the country and globe. In the U.S., it will be most challenging in rural areas.

“They have to be shipped under cold chain storage and they have to maintain cold chain storage from the time it’s manufactured until the time it’s injected into a person,” says Williams, who’s  also the editor-in-chief of AAPS PharmSciTech, the Official Journal of the American Association of Pharmaceutical Scientists. 

Cold storage can be tough to maintain, he says, estimating that 80% of the cost of these vaccines is tied to storing them properly.

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At the point of administration, the health care provider will thaw the vaccine. “And then the clock’s ticking because these are both mRNA based vaccines,” he says. “They degrade quickly and lose their vaccination power of their immunogenicity.”

When COVID-19 started, Williams’ research lab started focusing on the cold chain. They’re working with TFF pharmaceuticals and applying a thin film freezing technology, in essence, turning the liquid vaccine into power form.  While he can’t name names, Williams says his lab is working with all the big pharmaceutical companies.

The goal is to make the powder more shelf stable so the technician can mix a safe liquid with the powder at the time of vaccination. This powder would be a second generation type of application. It will be cheaper too since those cold costs won’t be a factor.



Williams has faith in both the Moderna and Pfizer vaccines.

“I trust it and I tell my family to trust it,” he says. “Because in the US, we have an infrastructure and the companies and the government are spending the money in order to be able to maintain the required temperature for that particular vaccine.”

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