The biggest challenge for COVID-19 vaccines is the cold supply chain

DISCLAIMER: All opinions in this column reflect the views of the author(s), not of EURACTIV Media network.

A Russian medical worker takes a trial vaccine against COVID-19 from refrigerator to prepare for a volunteer in a post-registration phase of the test at outpatient hospital number 68 in Moscow, Russia, 17 September 2020. [Sergei Ilnitsky/EPA/EFE]

Medical authorities and governments around the world should not only embrace one or more of the approved COVID-19 vaccines but must also be ready for the logistics of delivery, which includes a gigantic cold chain, possibly for temperatures as low as –80 °C, writes Kostadin Fikiin.

Kostadin Fikiin is an international R&D project manager at the Technical University of Sofia (Bulgaria); member of the Executive Committee of the International Institute of Refrigeration; Chairman of the EHEDG Working Group ‘Food Refrigeration Equipment’.

Medical authorities and governments around the world should not only embrace one or more of the approved COVID-19 vaccines but must also be ready with the delivery logistics.

IATA recently pointed out that providing a single dose to 7.8 billion people would fill 8000 Boeing 747 cargo aircrafts, even neglecting the fact that any vaccine may require several doses. In addition, vaccines have to be stored at low-temperatures for which not all planes are currently adapted.

Earlier, Deutsche Post DHL alerted stakeholders that two-thirds of the global population are unlikely to have easy access to any COVID-19 vaccine preserved at freezing temperatures. The lower the temperature, the more troubles and costs are involved.

Nevertheless, UPS has started building a couple of capacious facilities for frozen storage (in Louisville, Kentucky, US, and Venlo, the Netherlands), each exceeding the area of a football field.

These “freezer farms” consist of a multitude of nearly two-metre-tall cuboid-shaped freezers set at –80 °C and capable of holding millions of doses of frozen COVID-19 vaccines to promptly ship them across the world.

Although UPS are not yet disclosing the prospective freezer farms’ clients, it is not difficult to guess who might benefit from such deep-freezing temperatures. The vaccine candidates of Pfizer and BioNTech need to be kept at around –70 to –80 °C.

It is pretty clear that, except the innovative mobile freezer-farm units, the existing cold chain (and especially the refrigerated transport) is not prepared to cope with these low temperatures.

Fortunately, a relatively simple solution exists – good old dry ice (solid carbon dioxide), which sublimates at −78.5 °C, might be employed as a refrigerating medium, thus avoiding the need for on-board refrigerating units.

Pfizer said their vaccine must be stored at –70 / –80 °C for up to 6 months or in specially designed shipping containers (“dry ice packs”) for up to 10 days. Once taken out from the containers, the vaccine can be kept unfrozen for one day at 2-8 °C or a maximum of 2 hours at room temperature.

The company is now trying a less complex alternative to make the vaccine stable at higher temperatures.

Moderna Inc. initially stored their vaccine at –70 °C but later succeeding in developing storage and shipping at –20 °C maintained for up to 6 months. The vaccine can endure in an unfrozen state for up to 10 days after thawing. Moderna is also working to make the vaccine stable at higher temperatures.

The label of Russia’s Sputnik V vaccine stipulates “Storage at a temperature not higher than –18 °C. No storage of an unfrozen preparation is permitted.”

Obviously, this last couple of vaccines could take advantage of pre-existing cold-chain infrastructure, originally designed for preserving or distributing frozen foods at the standard temperature of −18 °C.

Sanofi and GlaxoSmithKline (GSK) are partnering on another vaccine-making endeavour. Translate Bio Inc., a smaller US-based collaborator of Sanofi earlier proposed a Moderna-like mRNA vaccine variant to be kept at –80 °C.

Several COVID-19 vaccines under testing do not require deep-freezing. Good examples are the experimental vaccines of Johnson & Johnson, AstraZeneca (with the University of Oxford) and Sanofi-GSK, expected to be kept and shipped in an unfrozen state.

A number of companies, e.g. CureVac, are working on stabilising the molecule at higher temperatures, for example by freeze-drying. Although unfrozen (chilled) vaccines seem to be more appealing for most stakeholders, their long-term stability and resulting shelf life remain a challenge.

Any failure in the cold-chain integrity is disastrous

Providing every human being with fast access to COVID-19 vaccines, at immunisation sites all over the planet, is not going to be an easy exercise. Everyone who needs a vaccine should get it anywhere in the world. Nobody is safe until everybody is safe.

The European Commission has negotiated on behalf of EU27 and has signed its first contract with AstraZeneca. A vaccine against COVID-19 for all EU member states will be purchased. A donation to lower- and middle-income countries is also foreseen, along with supply to non-EU countries in Europe.

Thus, EU27 are enabled to purchase 300 million doses, with an option for further 100 million doses to be distributed on a population-based pro-rata basis. The deal follows the advice of the “Inclusive Vaccine Alliance” (Germany, France, Italy, and the Netherlands).

While AstraZeneca’s vaccine has temporarily been put on hold as a vaccinated volunteer needed to be hospitalised, the Commission signed a second contract with Sanofi-GSK for up to 300 million doses for the EU27 and reached an outline agreement with BioNTech and Pfizer for 200 million doses, with a possible extra of 100 million doses.

Hence, Pfizer has already activated their deep-frozen supply chain and production site in Belgium.

The WHO reports that over half of vaccines are wasted globally because of temperature-control logistics and shipment-related issues. While the AstraZeneca product will likely require a chilled, rather than frozen, supply chain, maintaining a proper chilled chain is not less sophisticated than a chain for frozen commodities.

New EU member states and candidate countries of Central and South-Eastern Europe still have substantial gaps and deficiencies in their cold-chain infrastructures. In some cases, cold chains in developing countries are so scarce that any vaccines shipped there might go in vain.

Before dispatching any vaccine, the Commission and national governments should clarify each country’s cold-chain situation. Wherever necessary, reasonable financial support should be provided – it will be much wiser and cheaper to strengthen the cold chain than to lose large amounts of valuable biotechnology products.

To avoid monopolisation, it is highly desirable to count on universal cold chains enabling diversified supply from multiple freely competing vaccine providers. A level of transparency for public authorities and civil society representatives must be ensured as well.

Biotech and cold-chain experts must amalgamate their skills enough in advance in order to establish optimal handling and transportation regimes, incentives, standards, protocols and legislative documents regarding the cold supply chains for COVID-19 vaccine. In such a way, any unexpected circumstance can be tackled in a timely manner.

Otherwise, the vaccine provider might unexpectedly surprise stakeholders with a laboratory-compiled list of requirements which may turn out to be inapplicable in the real environment of cold-chain industry.

Last but not least, a transparent and sustainable temperature-controlled chain for vaccines cannot exist without today’s information and communication technologies. While many people regard cold chain as something guaranteed, failing to address its specific needs becomes a dangerous slippery slope.

Both EU and national authorities must join efforts to build a fully traceable, continuous and ubiquitous vaccine cold chain which is not at all an extravagance but represents a must of the present-day knowledge-based economy.

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