A vial’s last mile
For a country to receive Pfizer vaccines, it needs to have the capacity to store ultra-cold medical items.
While this isn’t a problem for wealthier nations, poorer countries are less likely to have the necessary infrastructure in place.
Upon arrival in a country, the shipment goes into a deep freezer, typically at the airport or a central storage facility, until it is ready to be used. The vaccine has to be kept in ultra-cold storage until within about a month before it’s injected into someone’s shoulder.
In poorer countries that do have the right infrastructure, such as Bangladesh, distribution still needs to be restricted to a few select hospitals in large urban areas where there are ultra-cold storage facilities. For example, Bangladesh will use Pfizer vaccines at seven hospitals in its capital city, Dhaka.
The frosty journey of the Pfizer vaccine itself is just one part of getting people their jabs. Ancillary supplies needed for vaccination include special syringes delivering a 0.3-milliliter (mL) dose, needles, sterile alcohol pads and personal protective equipment for the health care worker delivering the shot.
Preparing the injection of the Pfizer vaccine requires a complex dance. First the nurse thaws the vaccine in a refrigerator to a range of 36 F to 46 F (2 C to 8 C), where it can be held for up to 31 days. Just before vaccination, the nurse brings the vial to room temperature of 36 F to 77 F (2 C to 25 C), at which it can survive no more than six hours.
Because the Pfizer vaccine is shipped as a concentrate, the nurse needs to dilute it with 1.8 milliliters of saline, resulting in a mixture sufficient for six doses.
There’s a further complication in that many low- and medium-income countries use syringes that ensure a fixed maximum dose and are automatically disabled after single use. This takes away the guesswork and prevents mistakes. UNICEF is responsible for delivering these extra supplies to poorer countries that are getting their vaccines through COVAX, the global initiative set up to distribute COVID-19 vaccines to low- and middle-income countries.

The last step of the process before inoculation involves diluting the vaccine with saline to create 0.3-milliliter doses. AP Photo/Jae C. Hong
A monumental achievement
Other vaccines have much less demanding cold supply chain requirements, don’t require dilution and use syringes with standard dose sizes, allowing more countries to use them, including in rural areas.
Most of the COVID-19 vaccines approved for use by the World Health Organization, such as those made by AstraZeneca and Johnson & Johnson, require only standard cold storage of 35.6 F to 46.4 F (2 C to 8 C).
I focused on Pfizer in part because it makes up the lion’s share of doses donated by the U.S. to COVAX.
As of Aug. 22, 2021, a total of 4.97 billion COVID-19 vaccine doses had been administered, a feat unimaginable in the fall of 2020. But global coverage has been highly uneven. While a little over half of the population in high-income countries have been vaccinated, only 1.4% of low-income populations have received theirs. Many of these countries are in Africa.
The development of several vaccines, 10 of which are WHO-approved, many within a year, was a monumental achievement of science and global collaboration – especially since it previously took on average a decade.
But creating supply chains to deliver all those lifesaving vaccines to people all over the world will be an equally remarkable accomplishment.
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Ravi Anupindi, Professor of Technology and Operations, University of Michigan
This article is republished from The Conversation under a Creative Commons license. Read the original article.