The dry ice danger (CO2 risk) in the logistics chain of the Covid-19 vaccine

Dry ice enters the logistics chain of new Covid-19 vaccines to allow the storage of serum at very low temperatures. Using dry ice involves a CO2 risk throughout the vaccine supply chain. Here we’ll detail the dangers of dry ice and the CO2 detection equipment required for this refrigeration technique.

After the flu mask, hygiene precautions and various containment measures, the new Covid-19 vaccines incorporate the panoply of tools to fight the pandemic. At the end of 2020, after many months of development and clinical trials, various vaccines are being validated, or already in use by the various national health authorities around the world.

Different Covid-19 vaccine technologies will be available but some of the first vaccine solutions, including solutions developed based on the Messenger RNA (mRNA) such as the Pfizer-BioNTech vaccine, all have a common challenge: preserving their storage temperature. Indeed, to maintain their effectiveness against the virus, some of the vaccines produced to date require an ultra-low storage temperature, down to -70 ° C or even -80 ° C.

To preserve the effectiveness of the vaccine, storage at a -70 ° C temperature is a real logistical challenge for manufacturers, transporters and healthcare professionals. This temperature constraint represents a challenge for the organization of massive vaccination policies: vaccination centers, storage centers, hospitals, pharmacies, or medical offices must be able to preserve the vaccine’s cold chain.

Unlike conventional vaccines requiring a storage temperature down to -4 ° C, Covid-19 vaccine serum cannot be stored in medical freezers or conventional refrigerated transport. Faced with this constraint, various solutions are implemented: cryogenic units, ultra-cold freezers, transport under nitrogen, or dry ice. Among these solutions, dry ice is preferred by most specialized refrigerant carriers to guarantee the cold chain throughout the shipment of Covid-19 vaccines.

It is dry ice’s ease of production as well as its ability to adapt in many environments that makes this technique particularly effective for the storage of vaccines. It is also a technique widely used for storing meal trays in aeronautics.

Dry ice is simply the solid form of carbon dioxide (CO2). It is made by compressing CO2 at very low temperature by producing blocks of dry ice or small sticks or granules.

Dry ice has a temperature of -78.5ºC. It therefore makes it possible to generate cold very quickly and to participate in the preservation of the cold chain. It is used in various fields such as dry ice cleaning, food and pharmaceutical freezing, IT, chemistry, funeral parlors, dermatology, wine making, fire extinguishing equipment, refrigerated transport, or even for pest control.

If dry ice is particularly popular for the cold chain of Covid-19 vaccines for its cooling and preservation properties, it still presents certain dangers.

First of all, dry ice is an ultra cold solid that can cause severe burns. It is a solid that sublimates above -78.5ºC, reverting to its carbon dioxide gaseous form (CO2), a potentially dangerous gas when inhaled.

Colorless, odorless and invisible, gaseous carbon dioxide is a heavy gas which replaces oxygen, thus causing a real risk of anoxia in enclosed spaces.

The release of carbon dioxide in gaseous form when using dry ice involves potential exposure of various people to this gas. Packers, transporters, storekeepers and health system agents involved in the Codiv-19 vaccine distribution logistics chain are indeed subject to the exposure risk similar to the CO2 hazard in viticulture for example.

Almost undetectable by humans, the CO2 gas released in an enclosed space replaces oxygen. One kilogram of dry ice generates approximately 500 liters of carbon dioxide gas. Depending on the configurations of the equipment for transporting and storing the Covid-19 vaccine, the concentrations of carbon dioxide can have serious effects on the health of the present personnel. Indeed, from a 1% concentration in the air, CO2 causes respiratory discomfort, at 3% heart rate and the respiratory system impairment, and above 5% loss of consciousness that can lead to death. Potential exposure of the various workers in the Covid-19 vaccine’s dry ice cold chain therefore implies monitoring CO2 concentrations in ambient air with a portable CO2 detector for example.

Beyond conventional personal protective equipment such as special gloves and protective eyewear for handling dry ice, the supply chain for the Covid-19 vaccine requires the use of CO2 detection equipment.