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When it comes to planning how Covid-19 vaccines will be delivered to the people who need them, I hope hindsight will be used to learn from the past and the U.S. and other countries won’t repeat the many problems with vaccine supply chains encountered in the past.

The Public Health Informatics, Computational, Operations Research (PHICOR) team I lead has worked on vaccine delivery and vaccine supply chains around the world for nearly 15 years. A vaccine supply chain is the complex system of manufacturing transportation, equipment, personnel, locations, and processes involved in getting vaccines from where they are made to the people who will receive them.

It’s called a cold chain when vaccines must stay refrigerated or frozen throughout the delivery process. After all, most vaccines consist of perishable materials that don’t last long at room temperature. In fact, with the possibility of new mRNA Covid-19 vaccines that require storage under -80 degrees F or even colder, a “deep freeze” chain may be necessary

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The past decade has seen an unprecedented number of new vaccines being introduced to different countries around the world, so many that it was dubbed the Decade of Vaccines. Throughout this decade, my team has used computer simulation modeling to help evaluate, improve, and in many cases redesign vaccine supply chains for UNICEF, the World Health Organization, Gavi, the Bill and Melinda Gates Foundation, ministries of health of various countries, and a number of different nongovernmental organizations.

In the U.S. we have also helped local, state, and federal governments respond to infectious disease threats. During the 2009 H1N1 influenza pandemic, for example, the PHICOR team was embedded in the Department of Health and Human Services, assisting with the national response, using computer modeling to help plan the rollout of the new H1N1 flu vaccines.

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From this vantage point, I offer 10 lessons that should have been learned from the past that need to be considered in 2020:

Vaccine supply chains are complex, and can make or break Covid-19 vaccination efforts

I’m surprised — though perhaps I shouldn’t be — at the relative lack of attention being given to the vaccine supply chain. Much of the talk has focused on the development and testing of the new Covid-19 coronavirus vaccines and, to varying degrees, how they will be financed. Talk about how they will be delivered has been comparatively limited and vague.

Few people across the country have a clear idea of how exactly the Covid-19 vaccine supply chains will be organized.

Vaccine supply chains have historically been neglected and underappreciated.

A major part of my team’s work since 2007 has been trying to get more people to pay attention to these chains, since vaccines can’t really do their thing without actually being delivered to people. Getting decision-makers’ attention hasn’t been straightforward. The assumption on their part is often that, once vaccines reach the market and are paid for, vaccine delivery is the easy part and they can somehow magically appear in people’s arms and mouths. Perhaps the dearth of toilet paper on store shelves this spring should be a lesson in the challenges of supply chains.

Since the design and operations of vaccine supply chains are complex — too complex for most people to understand and address without assistance — we have developed and used computer simulation models of vaccine supply chains to help a wide range of decision makers in the same way that meteorological, air traffic control, and manufacturing models have helped decision making in those fields.

Don’t assume that current vaccine supply chains are sufficient to deliver Covid-19 vaccines

Before the Decade of Vaccines, we learned that vaccine supply chains in many countries were not ready for new vaccines such as the rotavirus, pneumococcal, and meningococcal vaccines. In fact, many weren’t even ready to handle the vaccines that they already had.

Their supply chains had inadequate storage, transportation, and personnel capacity, leading to major bottlenecks and the discarding of many vaccine doses because they never made it to their destinations. This led to missed opportunities to avert suffering and deaths, as well as substantial monetary costs.

During the 2009 H1N1 flu pandemic, the U.S. federal plan was to use hubs designed by the McKesson Corporation, a pharmaceutical distribution company, to deliver vaccines to each of the states. In many cases, the states then used the supply chains they already had in place to deliver the seasonal flu vaccine. This led to some vaccination locations receiving too many vaccines and others getting too few.

Routine vaccine delivery is one thing. Getting massive amounts of the population vaccinated as quickly as possible is completely different. Current vaccine supply chains aren’t designed to vaccinate so many people so quickly. Add in the problem that most existing supply chains don’t currently have the capability of storing and transporting vaccines at -90 degrees F and it becomes immediately apparent that current supply chains aren’t adequate for Covid-19 vaccines.

Factor in Covid-19 vaccine wastage when planning vaccine production, delivery, and administration

There are two types of vaccine wastage: closed-vial and open-vial.

Closed-vial wastage occurs when vaccines must be discarded without even being opened. This happens when containers are broken, or when the vaccine becomes unusable because it has been exposed to temperatures that are too cold or too warm.

Open-vial wastage occurs when a vaccine container that holds multiple doses of a vaccine (such as a 10-dose vial) is opened but only some of these doses are used. Depending on the type of vaccine (freeze-dried, liquid, and the like), the remaining doses may need to be properly stored and used within a few weeks, or they may need to be immediately discarded to prevent contamination.

The greater the vaccine wastage, the greater the costs and the more vaccines that need to be delivered through the vaccine supply chain. In this way, wastage rates can greatly affect vaccine supply chain design and operations.

Understand that the rollout of Covid-19 vaccines will affect the delivery of other vaccines, and vice versa

Other infectious diseases haven’t stopped being threats just because the Covid-19 pandemic emerged. There is still a need to continue giving routine vaccines like shots for measles, mumps, and rubella. It’s not as if all existing refrigerators, freezers, and transport vehicles can be coopted by the Covid-19 vaccine supply chain. Our work has shown how new vaccine introductions in countries such as Mozambique and Thailand derailed the delivery of all other existing vaccines.

Cold chain design and supply chain operations for the Covid-19 vaccines must account for all other existing vaccines.

Coordinate the design and packaging of Covid-19 vaccines with the design and operations of the Covid-19 vaccine supply chain

Our work has shown that even small changes in the size of vaccine containers and packaging, and the number of doses per container, can substantially alter vaccine supply chain operations. In 2006 and 2007, the introduction of the rotavirus vaccine in Latin America was derailed because the packaging was too large and occupied too much space in refrigerators and cold transport devices. This clogged up the supply chain for this vaccine and also impeded the flow of other products. As a result, manufacturers had to go back and redesign the rotavirus vaccine packaging, leading to delays and missed opportunities to alleviate suffering and deaths.

While manufacturers may design vaccine containers and packaging based on their production needs and what is best for their assembly lines, they must also consider how packaging may affect overall supply chain operations.

Account for the dosing schedule of Covid-19 vaccines

The number of vaccine doses needed per person greatly affects supply chain operations and design. It appears as though Covid-19 vaccination may require two doses per person, administered on two separate occasions. This effectively doubles the total number of vaccines the supply chain needs to deliver. This is further complicated by the fact that there will likely be more than one vaccine on the market and that, in the case of the AstraZeneca vaccine, the first dose of the vaccine may be different from the second one. All of this will necessitate an integrated information system that can keep track of who has received the first dose of which vaccine and when they need to be reached for a second dose of the appropriate vaccine.

Develop clear strategies that consider the different Covid-19 vaccines, their production schedules, and their target populations

It is likely that multiple Covid-19 vaccines will be licensed for use. Each will have its relative strengths and weaknesses based on effectiveness, duration of protection, side effects, dosing, storage requirements, and costs. Different vaccines could have different target populations.

Vaccines with more challenging storage requirements, like deep-freeze equipment, may be limited to locations that can support such requirements. Moreover, each vaccine will probably be produced in different stages or waves. All of this will require substantial coordination. One thing is for sure — plans will change. As we saw in 2009, the production schedules for the H1N1 flu vaccines changed from week to week. As a result, we had to continuously update our models to account for delays in vaccine availability.

Don’t overlook the Covid-19 vaccine accessory supply chain

Vaccines don’t just jump from their containers into the arms of the recipients. A number of different accessories are needed to deliver them, including syringes, needles, alcohol swabs, rubber gloves, and other personal protective equipment to protect the personnel administering the vaccine, anything that’s needed for record-keeping, and more.

As we’ve already seen during this pandemic when shortages of cotton swabs affected Covid-19 testing, missing one or more of these components can affect vaccination rates and the vaccine supply chain. Each of these products either needs to be part of the Covid-19 vaccine supply chain or in supply chains that are coordinated with other supply chains so all necessary products are in stock.

Don’t neglect populations that are harder to reach or harder to vaccinate

A vaccine supply chain is not like a supply chain for candy bars, beer, or other luxury goods. You can’t ignore those who are seemingly too difficult or too costly to reach, such as those who live too far from traditional health care locations or who don’t frequent them. The supply chain needs to reach those in lower-income neighborhoods, distant rural locations, and religious, cultural, or social groups that feel separate or disenfranchised.

As a result, the design and operations of different parts of the supply chain can’t be the same everywhere but instead must be tailored to different circumstances.

Ensure transparency and communication across all parties

It’s not enough to come up with a vaccine supply chain plan and design. Everyone involved needs to know what the plans are so they can coordinate accordingly. Personnel ranging from health care professionals to those working along all nodes of the supply chain must know when they need to be available and how to handle different issues. People wanting to be vaccinated must be clear on where to go and when, otherwise long lines, stock-outs, and unfulfilled demand can result. Vaccination sites and storage locations need to coordinate in case circumstances change and policies need to be altered. For example, a vaccination location that runs out of vaccines may need to get vaccines from other locations that have surpluses.

These certainly aren’t all of the Covid-19 vaccine supply chain issues that may emerge. The year 2020 has brought many challenges, including problems coordinating the national response to the Covid-19 pandemic. The success of vaccines against it depends not only on the characteristics of vaccines but whether they are actually delivered to everyone. As history has shown, vaccine supply chains are far more complex than many people realize.

Hindsight may be 20/20, but only if you carefully look at history and learn from it.

Bruce Y. Lee is an internal medicine and public health physician, professor of health policy and management at the City University of New York Graduate School of Public Health and Health Policy, and executive director of the Public Health Informatics, Computational, Operations Research team.