Thursday, November 30, 2023

Keeping covid vaccines cold isn’t easy, but these ideas might help

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Then there are the refrigerators themselves.

In 2009, engineers at the Bill and Melinda Gates Foundation in Seattle began designing an off-grid refrigerator for use in places with little or no cold chain infrastructure.

The result was the Arktek – a super barrel-sized thermos for refrigerating vaccines or other biological samples. Different substances can prime it to store materials at different temperatures: dry ice can keep samples at -80 ° C, while a mixture of water and ethanol can set the temperature to around -20 ° C. If it contains 450 vials, they will stay refrigerated for three to four weeks, while 750 vials can stay cold for up to two weeks, says Daniel Lieberman, Arktek’s inventor at GHLabs, a non-profit organization created by the Gates Foundation. Since the device does not have any electrical parts, it is extremely difficult to break: it will only be rendered useless if someone manages to puncture the vacuum seal.

The device was first tested in 2014, when Ebola ravaged villages in West Africa. The vaccine available at the time, developed by Merck, required refrigeration to -80 ° C. When Arktek was deployed in the field in 2015, it played a role in vaccinating 8,000 people and helping to stem the disease. Ebola epidemic.

Since then, the roughly 3,000 units have remained in countries across Africa, says Lieberman, and are used to store routine vaccines against diseases such as measles, polio, chickenpox and hepatitis. Various international organizations, such as UNICEF and Médecins sans frontières, buy Arkteks for countries in need. About 1,000 new units have been manufactured specifically to handle the distribution of covid-19 vaccines, says Shouda Li, general manager of the device’s manufacturer, Aucma, based in China. These new units will be sent to South and Southeast Asia, the Middle East and some countries in Latin America, Li said.

There’s another experimental approach to development – one that would skip the cold chain altogether, Weissman says. Some developers have dehydrated current covid vaccines. Dehydration would make the dose stable at room temperature indefinitely, Weissman says, until it is reconstituted just before use. The downside is that it would make the vaccine more difficult to produce: dehydration adds additional processing, which would dramatically increase manufacturing costs. Always, Pfizer says he could have it ready by 2022.

For mRNA vaccines, reliable storage at room temperature would be a game-changer, removing a long-standing barrier to vaccines for all.

Fuller says: “The cold chain has always been a problem for [the] vaccine distribution, and this only worsens in a pandemic where it is so crucial to immunize all corners of the globe as quickly as possible.

This story is part of the Pandemic technology project, supported by the Rockefeller Foundation.


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