There are several! We talked about some of these challenges earlier this year.
Some people talk about the scale. For example, it will take approximately 500 million doses to vaccinate a significant portion of the US adult population, because most of the vaccines require two doses. As a comparison, this year we have a supply of 198 million doses of influenza vaccine, and the H1N1 pandemic response distributed more than 100 million doses in emergency settings. So the scale is impressive, but not insurmountable, especially given that the systems will build upon previously used practices.
One challenge is the cold chain that is required, especially for a vaccine like the one from Pfizer, which currently needs to be stored at -70 degrees Celsius (-94 degrees Fahrenheit). That is much colder than our freezer temperatures. Pfizer has developed a special thermal shipping box that can have dry ice added every five days for up to a total of 30 days. Once thawed it should be kept at 2-8 degrees C (refrigeration) for no more than five days. The shipping box contains about 1,000 to 5,000 doses, so it is likely to be more appropriate for cities, or locations that will host mass vaccination clinics.
The Moderna vaccine can be stored at -20 degrees C for months or at 2-8 degrees C for up to 30 days. Those shipments will contain a minimum of 100 doses each, so it may be appropriate for smaller locations, including rural ones. Fortunately, from the initial available data, those two vaccines have similar profiles in terms of safety and efficacy.
A third challenge is managing and using the information across the whole system. Our public health system is decentralized, with multiple entities making decisions. There are several information systems that have different functions and do not all talk to each other. On an everyday basis, the public health system does not need to have a robust information system tracking millions of products to their final destination for rapid response to changing supply and demand. There are also some new information systems being deployed; this could be helpful or it could add to the complexity.
Another challenge is people. Namely, how do we reach people, including in fair and equitable ways? How do we make sure that people have trustworthy information about safety and efficacy?
We are already seeing misinformation campaigns, and there are documented concerns around vaccine hesitancy. The people managing logistics systems should remember that human beings are the ultimate consumers. That means logistics should include humans in the loop in multiple ways to support equitable, just outcomes that take into account patient opinions.