CO₂ Detection for Dry Ice Sub-Freezing Temperature Storage and Transport of COVID-19 Vaccine

Posted on December 7, 2020

There’s a lot of excitement about the COVID-19 vaccines finishing up their Phase III trials and giving us hope for putting an end to the current global pandemic. While this is great news, the next hurdle will be distributing Billions of doses of vaccine across the globe while maintaining strict temperature limits to ensure vaccine effectiveness. Each vaccine has different storage temperature requirements for both short and long-term storage and this needs to be maintained from the lab to the vaccination site:

• BioNTech /Pfizer/Fosun: -94F / -70C
• Oxford University/AstraZeneca: 36F / 2C
• Janssen: 36F / 2C
• Moderna: 36F / 2C
• Novavax: 36F / 2C
• Sputnik V: -4F / -20C

The mRNA vaccine from Pfizer has the lowest temperature requirement at -94F/-70C but even the others that can be stored at fridge temperatures will likely exceed the capacity of today’s cold-chain logistics system if we hope to vaccinate a significant portion of the global population. The likely solution is large-scale usage of dry ice (frozen Carbon Dioxide, CO₂). Dry ice has the unusual physical property of sublimation at -109F/-78C. Sublimation, unlike melting, means the solid form of CO₂ converts directly into gas instead of a liquid when warmed past this temperature. Dry ice has been used for some time for the delivery of food products by mail (if you’ve ever ordered steaks or pies by mail, this is how they keep it frozen for the journey). This will ensure that vaccines can be transported to all corners of the globe with simple insulated containers. These same containers can also double as short-term storage containers while the vaccines are administered.

Dry Ice and Gas Safety Detection

The benefits of CO₂ are many, but the one drawback is that as the dry ice sublimes, the result is the creation of CO₂ gas. For every 2.2 lbs (1 kg) of dry ice, 541 liters of CO₂ gas is created. In small quantities, dry ice won’t create enough gas to cause concern but as we ramp up the global distribution effort, the amount of dry ice used will be substantial. If many transportation containers are staged in one area the collective gas emissions could be enough to be a potential safety hazard to personnel in the area. Luckily, CO₂ gas detection is something Bacharach has a lot of experience with and our CO₂ detectors are among the best in the business. The MGS-400 series of detectors can be installed in areas where CO₂ could accumulate and warn personnel before the levels become dangerous. Also, due to the 24 VDC (or 24 VAC) power supply, and optional IP66 protection, mounting them in portable applications is also possible. For large-scale storage facilities, our aspirated CO₂-MZ unit can monitor up to 16 locations per unit with the ability to alarm locally and also inform facility management of issues before they become hazardous to personnel.

Enclosed Spaces

In enclosed spaces where CO₂ build-up is a potential hazard, we recommend alarm settings well below the short-term exposure limit (STEL) of 15,000 parts per million (ppm) while European regulations use 30,000 ppm as the STEL. Our warning and alarm set point levels can be independently configured and we recommend the following levels: