Will temperature requirements constrain the COVID vaccine rollout?

Most common vaccines are distributed at temperatures between 2°C and 8°C (36F-46F). The COVID-19 pandemic has shortened the time period between approval phases to meet ambitious schedules, and the temperature requirements for distribution, which are rigorous due to a lack of stability data, vary across the different vaccine candidates. The Pfizer-BioNTech vacccine is the only one that will require dry ice; all the other vaccines in Phase 3 trials, including Moderna, will only need passive boxes with ice packs to maintain required storage temperatures in an insulated enclosure. This is standard procedure when transporting pharmaceutical, seafood or frozen products across the air cargo industry, so Cargo Facts Consulting does not foresee major constraints in transporting most COVID-19 vaccine candidates.

Table 1 shows the temperature requirements for COVID-19 vaccines that have confirmed orders worldwide. Table 1 – Storage temperature requirements for COVID-19 vaccines

Source: Duke Global Health Innovation Center

The Pfizer-BioNTech vaccine was the first approved vaccine for widespread use; it requires storage temperatures of -70 C and can last in specialty freezers for up to six months. Pfizer developed a specially designed temperature-controlled thermal container that uses dry ice to maintain the recommended storage conditions of -70 -10 C for up to ten days, if unopened. With regular refills of dry ice, the packaging can maintain that temperature for up to 30 days; after that, the vaccine can be stored for five days at refrigerated 2-8 C. Figure 1 shows an overview of the cold delivery chain for this vaccine. Figure 1 – Overview of Pfizer-BioNTech COVID-19 vaccine ultra-cold delivery chain

The Moderna vaccine is the only other candidate in a final approval phase that requires freezing storage conditions of -25 to -15 C for up to six months but does not require dry ice. These vaccines can then be stored at refrigerated temperatures between 2 -8 C for up to 30 days before vials are punctured, so the shipping and distribution processes are less complex.

With governments trying to distribute millions of vaccines in the next months, the demand for dry ice has skyrocketed and has led to supply shortages. “Dry ice” is the common name for solid carbon dioxide or CO2, a noncombustible and nontoxic refrigerant frequently used in the food, industrial and pharmaceutical industries. The only raw material of dry ice is carbon dioxide, the by-product of gases emitted during the refinement of products such as ammonia, gasoline and ethanol.

Since the beginning of the pandemic, there has been a decline in the production of ethanol and gasoline, resulting in a shortage of this gas in the second half of 2020. Dry ice presents a challenge since it cannot be stored very long due to its short lifespan and its sublimation from a solid into a gas, releasing carbon dioxide into the surrounding area as it does so, and becoming hazardous inside an enclosed space, such as an aircraft.

The Pfizer-BioNTech vaccine is currently manufactured in Belgium and the U.S. so most distribution will take place domestically in Europe and North America, where ground will be the preferred transportation mode. Pfizer has developed a special transport box that holds 5,000 doses of its vaccine and 23 kg of dry ice. While we have counted a total of 1.12 billion doses confirmed worldwide, only about 14% of that total — or 159 million doses — will be shipped intercontinentally, requiring about 732 tonnes of dry ice. This share could be higher as cargo operators distribute the vaccine in regional networks in the EU and US, but we don’t expect more than 25% of this vaccine to be moved by air. However, all Pfizer doses will require dry when transported, adding up to a total of 5,040 tonnes of dry ice for all confirmed orders. This figure does not take into account the refills of dry ice needed every 10 days if doses are not stored in specialty freezers.

Since the sublimation of dry ice produces CO2, the U.S. Federal Aviation Administration (FAA), the European Union Aviation Safety Agency (EASA) Boeing and Airbus all publish guidance as to how much dry ice an operator may carry. Passenger aircraft and freighters vary widely as to the dry ice loads they may carry; these limits are based on assumptions about the sublimation rate of the dry ice and the ventilation capacity of such aircraft. Cargo operators can follow their own calculations or adhere to the procedure suggested by either Boeing or Airbus, and since there is no specific limit established per aircraft type, we see differences in the allowable quantities of dry ice among operators.

All Nippon Airways (ANA) states that the allowance of dry ice on a passenger 777-300 is 800 kg while 600 kgs are permitted in a 787-9, 787-8 and 777-200. However, the capacity limit increases to 1,300 kgs for their freighter fleet of 777Fs and 767Fs. Meanwhile, Emirates estimates a 1,000-kg limit in the lower hold of its passenger 777 fleet, which is equivalent to 43 Pfizer boxes carrying 217,000 vaccine doses. Operators worldwide are working with aviation authorities to increase the dry ice limit allowance on their aircraft, with the FAA recently granting United Airlines permission to carry up to 6.8 tonnes of dry ice on some flights — the equivalent of 296 boxes holding 1.48 million doses.

Will temperature requirements constrain the COVID vaccine rollout?

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