Cold Chain Challenges Associated With Pfizer’s COVID-19 Vaccine Candidate
On November 16, 2020, Pfizer announced its COVID-19 vaccine candidate was more than 90% effective in phase 3 clinical trials.1
The vaccine requires a temperature of -75°C for storage. If the US Food and Drug Administration (FDA) were to approve the vaccine, it would be the most delicate vaccine on the market.2 The temperature for the current vaccine requiring the coldest storage on the market is about negative 25°C. Physician offices, pharmacies, and laboratories currently are not equipped with freezers that could get cold enough to safely store the Pfizer vaccine.
The distribution of the vaccine is being led by the Centers for Disease Control and Prevention (CDC), the Department of Defense, and Operation Warp Speed (a part of the Department of Health and Human Services [HHS]). Any disruption in the cold-chain could prove detrimental to the Pfizer COVID-19 vaccine.
Ultra-low temperature freezers are available, but CDC representatives have told states not to purchase them. The CDC’s plan is to maintain the vaccine with dry ice, which is currently in short supply in many parts of the United States. Pfizer will ship the vaccine in a box with dry ice, what is termed a “thermal shipper.” The vaccine can remain in the box until it is ready to be administered; at which point clinicians will remove the vaccine and then thaw, dilute, and inject it. Pfizer representatives state that the thermal shippers will need to be replenished within 24 hours of shipment arrival. If the vaccine is not used within 5 days, the dry ice must be replaced again, with the cycle continuing until vaccine usage. If the vaccine is removed from the dry ice and put in the fridge, it is only good for 5 days. Each vaccine vial contains 5 doses, which need to be given within 6 hours of dilution. If all 5 doses are not administered in this period, the remaining amount must be thrown away.
This whole process will need to occur twice, as the Pfizer vaccine is administered in 2 doses 3 weeks apart.
Health care providers are concerned about the challenges associated with the vaccine. Health care professionals are already overextended when treating patients with COVID-19; the addition of the Pfizer vaccine and its extensive stepwise process only adds to the stress.
The CDC, HHS, and Pfizer have not released any data to demonstrate how the thermal shippers will work. Additionally, there has been mixed information on the life of the thermal shippers. Various answers have been given, stating that the vaccine can be stored in the thermal shipper anywhere between 10 and 15 days before the dry ice needs to be replenished.
As state health officials prepare for distribution of the Pfizer vaccine, concern rises regarding glitches in the cold-chain system. Additional concern exists regarding skepticism of the vaccine. If the distribution does not go smoothly, public perception and mistrust of all COVID-19 vaccines could be altered.
—Audrey Amos, PharmD
References:
- Pfizer and BioNTech conclude phase 3 study of COVID-19 vaccine candidate, meeting all primary efficacy endpoints. News Release. Pfizer. November 18, 2020. Accessed November 18, 2020. https://www.pfizer.com/news/press-release/press-release-detail/pfizer-and-biontech-conclude-phase-3-study-covid-19-vaccine
- Cohen E, Bonifield J, Jenkins S. Pfizer’s ultra-cold vaccine, a ‘very complex’ distribution plan and an exploding head emoji. CNN Health. Published online November 10, 2020. Accessed November 19, 2020. www.cnn.com/2020/11/10/health/pfizer-vaccine-distribution-cold-chain/index.html