A shot in the arm

Source: Wikimedia This file is licensed under the Creative Commons Attribution 4.0 International license.

What’s new?

On 11 August, National Geographic described improvements being made in the processes to make vaccines, especially vaccines for COVID-19.

What does it mean?

While the US has ample supplies of COVID-19 vaccine (and a shortage of people willing to have the vaccine), most of the world needs more of the vaccine (and has plenty of people willing to have the vaccine). In addition to policy issues, such as the licensing of the vaccine, the rate of production of the vaccine affects the availability of COVID-19 and other vaccines.

Of the three types of COVID-19 vaccines (messenger RNA that conveys instructions to help the body fight the virus, inactivated virus to prime the immune system to produce antibodies, and a cold virus as a vehicle for immunizing material) each has its own method for production; the latter two are produced only in large batches.

A batch process requires weeks to grow host cells and then days to grow and process the vaccine.  The vat of cells eventually stops making product of sufficient quality; the vaccine eventually kills off the cells. Then the tanks must be properly cleaned and prepared for the next batch.

While the idea of change from a batch to a continuous process has been pursued since 1965, those approaches have still used large vats, seeking to siphon off the vaccine continuously. Recently an approach described in the National Geographic article has used 300-meter-long tube; it has been successful in a prototype. In this approach, fresh cells are continuously fed into the opening of the tube, another tube feeds in small quantities of the vaccine, and a pump keeps the fluid moving through the tube to the end where the vaccine and cell debris are separated. The new process is smaller and can be rapidly scaled-up when needed.

What does it mean for you?

The biggest point to understand from this article is that advances in product technology are always coupled with advances in process technology. Engineers work constantly to develop new products and to improve the design of existing products – and engineers do the same for processes, that is, they work constantly to develop new processes and to improve the design of existing processes.  The National Geographic article’s description of the new tube based process is an example of a new manufacturing process.

The Moderna and Pfizer vaccines are mRNA vaccines and these are new products. As Chemistry World states, “Large-scale production of such a vaccine has never happened before.” That article also says that Moderna and BioNTech have not released details on their manufacturing processes, but the processes is apparently not complicated: “The mRNA synthesis takes two hours, while making the vaccine takes a couple of days.” However, some of those steps are tricky.

The mRNA situation illustrates the interconnection between product design and process design. A new product may require a new manufacturing process. I can confidently predict that the world will continue to need new vaccines. It seems likely that mRNA vaccines will be an important tool in our capacity to counter new infectious diseases, so engineers will need to improve the processes for making mRNA vaccines. I am sure there are engineers busy on that task right now.

Manufacturing processes for different products can look similar. The National Geographic article describes how the inspiration for using tubes to manufacture vaccines can from observation of an oil refinery.

Product design and process design interact in many ways. Some changes in processes may enable higher quality also and the quality of vaccines is a crucial consideration in their manufacture. Different manufacturing processes can be harder or easier to scale. Some, as in batch processing, have an inherent scale, while a continuous process may be able to scale up or down more easily.

Once a product has somewhat stabilized, incremental product improvements and incremental process improvements continue to be developed. The cost of the technology for solar and wind power continues to fall dramatically largely because of advances in manufacturing processes.

Where can you learn more?

I am an industrial engineer. Most industrial engineers work in manufacturing, working on continuous improvement of manufacturing processes. The Institute of Industrial & Systems Engineers is the professional organization for such work.

This work is licensed under a Creative Commons Attribution 4.0 International License.

One thought on “A shot in the arm”

  1. Not to nitpick, but technically it’s not “messenger RNA” because it’s not really mRNA at all–it’s an artificial form of mRNA in which the uracil has been replaced by methylated pseudouracil. In nature, pseudouradine is found in tRNA, not mRNA.

    This change makes it much more stable, more likely to be taken up by a ribosome, and less likely to provoke an immune response. It also appears to give it a much longer half-life than mRNA. What else does it do? No one knows.

Leave a Reply

Your email address will not be published. Required fields are marked *