I'm no epidemiologist, but I support a number of global vaccination organizations. A layperson thread on how much work it takes to get each dose in a person's arm, and why it's so hard to tell exactly when vaccines will arrive and in what numbers

It’s hard enough to get actual vaccines that currently exist and are routinely made from factories to people’s arms. Vaccine supply chain logistics are a fiendishly complex mix of perfectly timed planes, freezers, trucks, camels (yep, seriously), ice boxes, canoes, more trucks.

This is the supply chain management policy for polio vaccines. It is 50+ pages, dealing with challenges like late planes, ice box melts, broken trucks, counterfeit vaccines, stolen vaccines, broken vials and the million potential breaks in the chain https://polioeradication.org/wp-content/uploads/2016/09/Cold-chain-logistics-and-vaccine-management-during-SIA_Nov2015_EN.pdf

This is Gavi’s supply chain portal (Gavi coordinates vaccination for most of the global south). It provides data to manage stock, expiry, loss, and leakage. It monitors vaccine flows, equipment status, personnel and the million other factors involved https://www.technet-21.org/iscstrengthening/index.php/en/

The polio vaccine exists. A COVID vaccine does not in the meaningful sense. Gavi is a 10 year org with the mandate to oversee global vaccine supply chains. No COVID vaccine has yet even finished clinical trials. There is no global oversight body for all possible COVID vaccines

There isn’t just one COVID vaccine manufactured in one way. There’s at least 3, possibly 6, maybe more, all made in different places, using different methods, needing different packaging, storage and transportation, to different places

Each COVID vaccine with its unique manufacturing, storing and packaging needs to get to a range of very different countries who have different capacities to store, in different amounts. See? It’s brain-breakingly complex

Each potential COVID vaccine needs specific, customized manufacturing and packaging facilities, for products that don’t actually exist. Many COVID vaccine researchers partnered early to concurrently build manufacturing facilities for a product they had no idea would even work

Pfizer has built huge super-cold storage plants as hubs. UPS has built vaccine hubs near key airports. Countries are trying to secure extra cargo planes. All in advance of any vaccine existing

The manufacturing is so challenging, the Gates Foundation pre-funded the largest global vaccines manufacturer, Serum Institute based in India, to make the Astra-Zeneca vaccine now, for if/when it gets approved, for distributing to poor countries https://www.nbcnews.com/news/world/promise-coronavirus-vaccine-factory-india-looming-fight-over-it-n1247834

Like, Bill and Melinda Gates paid for the manufacturing of 200m doses of a COVID vaccine nobody knows will even work, just so that poor countries have a supply, if it does work

Without India's huge vaccine manufacturing industry, we won't have enough vaccines for everyone. We have to then get the vaccines correctly packaged, labelled, stored and then moved by hook or by crook, to that last mile https://www.nature.com/articles/d41586-020-02507-x

So if you're wondering why nobody seems to know when your vaccines will get to your local clinic and in what quantity, it's cause the global vaccine supply chain is difficult in normal times. In COVID times, it's a fiendishly complex problem

And I apologize to actual vaccine supply chain experts for mangling and simplifying this. I've tried to do a layperson's thread (because I am one!) so I've probably got a lot wrong

And if you want to see how hard immunization is, @PakFightsPolio shows you the work it takes to immunize 30m children in a few months. Workers climbing glaciers, on donkeys, and traversing rivers with ice boxes on heads. Every. Last. Child