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Home / Health / The wild logistical journey of the high-tech thermos flask of the Ebola vaccine

The wild logistical journey of the high-tech thermos flask of the Ebola vaccine



The virus disease Ebola killed 25 people in the Democratic Republic of the Congo on May 26 and made 31 others sick. In response, treatment centers have emerged (two out of three people who have fled from one of these centers in Mbandaka City have died), and health workers are still receiving an experimental vaccine. People who have had contact with somebody with Ebola and their contacts will also get the admission. Heroic health workers take care of the sick and do epidemiological detective work. And the key to stopping the eruption before it becomes a nightmare could be high-tech synthetic ice.

In this sense of waiting-what, let's get up for a second. At the end of the Ebola epidemic in West Africa between 201

3 and 2016, during which 11,000 people were killed, a global network of researchers since its development after September 11 took an Ebola vaccine off the rack, where he had met metaphorically attacks. They introduced it to serious field trials, and these studies have confirmed the efficacy of the rVSV-Zebov vaccine currently being used by health authorities in the Congo.

About a dozen Ebola vaccines, rVSV-Zebov has a lot to offer. The VSV has vesicular stomatitis virus that does not infect humans, and here scientists have replaced a specific glycoprotein with one from the zaire strain of the Ebola virus (the "zebov"). It is a so-called live attenuated vaccine, a potent inducer of immunity that requires only one dose.

Goodies; In 2016, GAVI, the Vaccine Alliance, has set 300,000 doses in the event of another outbreak, as is currently the case. Only one problem: "This vaccine, if I have to be completely honest with you, started to work pretty cold with the vaccine and then they tried to bring it to a normal temperature," says Seth Berkley, Epidemiologist and CEO of GAVI. "They did not do all the stability and process work they could do." In other words, the developers of the vaccine had no time to figure out how to formulate it to be stable at the usual 2 to 8 ° C (that's 35.6 to 46.4 degrees if you're Team Fahrenheit).

Point is, all signs indicate that the vaccine works. But until you're ready to use it, you must keep it waaaaay colder, frozen at -60 to -80 degrees Celsius. (Yes, good, -76 to -112 degrees F, you barbarians). This is a particularly annoying version of a problem known to vaccine manufacturers: the cold chain.

In parts of the world where power is limited, even temperatures above or below freezing are challenging. To achieve this, a group of funders, including the Gates Foundation, went to Global Good, the science-hero arm of ex-Microsoft CTO Nathan Myhrvold's Intellectual Ventures, to develop a solution. Her answer was called Arktek, possibly the coolest cooler in the world.

Based on Dewars, which use industrial applications to contain things like super-cold liquid nitrogen, the Arktek is a double-walled vessel with a vacuum in between, held together with reinforced fiberglass. "They are trying to reduce all mechanisms of heat transfer between the warm outside and the cold inside," says Mike Friend, Principal Investigator at Intellectual Ventures. The vacuum reduces the convection. A shiny coating on the inner vessel reduces heat radiation. The low heat conduction of the reinforced fiberglass prevents heat from escaping. "And then you need a thermal battery, so to speak."

In this case, this battery delivers cold, not heat. The original Arktek was simple water ice that had frozen in semicircular plastic containers and could then warm slightly above freezing. Eight of them placed in the Arktek would keep the thing at the right temperature for up to a month, even in the hottest equatorial heat. Once a month, the villages were able to get their vaccines and ice blocks from somewhere with freezers, and now everyone could be vaccinated. Intellectual Ventures developed the technology and licensed it for free to the Chinese refrigeration company Aucma to build the coolers.

Was it a perfect system? Well, on the occasion of having a slight cooling, some people have taken a slight advantage; A solar boiler technician reported an Arktek suspected of smelling fish during the inspection, and anything that keeps vaccines cold will do the same for beer. But still.

Ebola increased the stakes. To get below -60 ° F, as recommended by Merck, the manufacturer of the vaccine, you would normally use dry ice-frozen carbon dioxide. It's the right temperature, and it sublimates into a gas rather than melting into a liquid. This requires more energy so that dry ice is a great way to store cold. "But for Sierra Leone, Guinea and Liberia, the problem was that they could not get a reliable supply of dry ice, and power was also a big issue," says Friend. "The CDC and WHO were only able to set up camps with reliable power in the capital, and they had to take extreme measures."

That meant a whole new logistical effort. Local health workers and international aid organizations equipped warehouses with power supplies, alarm systems and switches, freezers below 80 degrees Celsius, air conditioners and more. Because the "ring vaccine" strategy scientists wanted to test in West Africa meant they had to go to Ebola cases and then have to find contacts and contacts of contacts to vaccinate. It could take days, and the vaccine had to remain arctic chilly most of the time.

WHO called Friend's team. It was November 2014; They had to find a solution by January.

Here comes synthetic alcoholic ice into play. Water ice was not cold enough. Dry ice was not available. Friend needed a different thermal battery.

He searched for a category of chemicals called phase change materials, PCMs, synthetic molecules that were built with specific freeze-thaw cycles. And he found one: a proprietary PCM based on a denatured alcohol made by a small company in England. "The owner is a very reserved man, I think Eastern European, trying to get information from him was a bit challenging," says Friend. For example, why exactly did he do this stuff? "It was a special request, he did not give much details about who had requested it."

It was not really important; He was ready to do it for Friend in a few weeks. "Then we had to confirm that it actually worked and actually simulated what was being done in the field," says Friend. They loaded the PCM into the semi-circular plastic tiles, froze them, and loaded Arkteks into rooms that had heated to West African extremes. Then they opened and closed them like sales reps and monitored the inside temperature. The PCM was flammable; it would have to fly to West Africa with a military cargo plane. The Freundeskreis team was not even sure that the Arktek would withstand even the lower temperature, let alone the plastic trays used to store the vaccine. "We had to bring them to temperature, let them vibrate, drop them and see how they would work," says Friend. "Luckily everything was fine."

Not everything. The high density polyethylene used to make the plastic tiles did not match the PCM; After a few freeze-thaw cycles, the PCM began to exit through the bolted top. They could smell it. But Friend's team had made aluminum containers just in case.

The aluminum containers worked. Modified Arkteks are at the heart of the logistical strategy for the Congo full-ring vaccine. The WHO uses two freezers, which can be stored in Kinshasa, the country's capital, below -86 degrees C to store vaccine and freeze the PCM ice packs and a power source and generator. Mbandaka, a city of perhaps 1.3 million people, in which four cases have occurred, has two more freezers, a 300-liter freezer and a 600-liter freezer. And they use 16 arkteks in the field. You can keep the vaccine below -65 ° C for five days, and experience has shown that it works between two and eight degrees Celsius after two to eight weeks. (Boyfriend has now slightly modified the PCM so it's less flammable.)

"People said at first, oh my god, that will be impossible," Berkley says about the cold chain. "It's not ideal, but it will not be the problem."

In fact, with the vaccine safe, greater concern will make people feel comfortable when they take it. "Everyone knows what a vaccine is, but usually it's either given as part of a campaign or as part of a routine vaccine," says Berkley. "The idea of ​​going to a community, visiting the family of someone who is ill, and just vaccinating that family and the people around them is something that needs to be socialized." People working in the area who speak the language, Anyone from the Democratic Republic of the Congo, has to convey this message and seek the consent of the vaccinated. But if the program works, it could mean that people are not so afraid of treatment centers and talking to epidemiological workers trying to find the rings of people who need to be vaccinated.

Whether ring vaccination works fast enough to be seen. Researchers will use data from this application of rVSV-Zebov and other even more experimental therapies – the antibody medicine ZMapp and the antiviral drugs favipiravir and GS-5734. According to Nature the Congolese Ministry of Health and an ethics committee still have to approve these other drugs. "It was very gratifying to develop something that came about as a result of all these people," says Friend. "The fact that the vaccine was effective and we were able to do it is amazing." Good epidemiology, treatment and a vaccine (thanks to this Neoeis) are still the best hope of the Congo.


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