A vital role: load cells and vaccine production

Published On: June 25 2020


The race is on to develop the first effective COVID-19 vaccine, and it’s a very fast race indeed. Processes that normally take years are being compressed into a matter of months. Vast sums are being invested to ensure teams from across the world have the resources to accelerate their work.

Scientists in the UK are at the forefront in developing a vaccine, with clinical trials already underway by a team at the University of Oxford, led by Professor Adrian Hill. Professor Robin Shattock and his team at Imperial College have designed a self-amplifying RNA vaccine using a piece of genetic code and are moving to human trials within a six months timeframe.

The demand for any effective vaccine will be huge, and it’s small wonder that large pharma giants such as AstraZeneca have signed a $1.2billion deal with the US government to produce 400 million doses of Professor Hill’s as yet unproven vaccine (at time of writing). This is in addition to a deal with European governments for up to 400 million doses, and with the UK for 100 million doses.


How do you manufacture a vaccine?

Manufacturing vaccines at scale is a challenge that requires precision to deliver every precious drop in a precise dose to waiting populations across the world – and load cells are playing their part.

The Chinese biotech company CanSino produced vaccines for the ebola virus, and so already have the equipment required to extract RNA fragments of COVID-19 virus and insert them into the Adenovirus to form what is known as a “recombinant protein vaccine”.

As an article in Pharmaceutical Online explains:

“This combination-product was put into a bioreactor, where three compact load cells are installed underneath. In this bioreactor, the combination products are scaled-up and purified under precisely controlled conditions to create the basis for the vaccine. The PR6212 load cell is used here to measure weight in real time so that adjustments can be made as quickly as possible, if required.”

The process relies on accurate data at all stages, as one bioreactor manufacturer explains:

“The load cell results are highly accurate and have a failure class of only 0.04%, even though the bioreactor is constantly stirring the materials, thus making precise measurements more demanding. The load cells are connected to a PR 6130/65S junction box, which has an IP protection of up to IP69, making it extremely resistant from outside forces. The data is then transmitted to a computer system by a PR 5211/10 transmitter.”

Bioreactors are key to the production of vaccines and other cell lines, and come in a variety of capacities from 50 litres to an impressive 2000litres. Some can be ‘dialled down’ to operate with just 20% of maximum load so that the same equipment can be used for seed reactors and lowering costs. Load cells are used for weight measurement, and need to be accurate in an environment where the liquids in the bioreactor single-use bag needs to be heated and agitated during production. The load cells accuracy is usually ± 0.02% of max bag volume.


Vaccine development timeline

Making vaccines is a complex and expensive business, and normally very time-consuming too. The World Economic Forumestimate that the average timescale of vaccine from first concept to patient delivery is around a decade:

  1. Discovery research • 2-5 years with up to 100 potential vaccines
  2. Pre-clinical • 2 years, 20 potential vaccines
  3. Clinical development
    1. Phase 1: is it safe? 1-2 years, 10 potential vaccine
    2. Phase II: does it activate an immune response? 2-3 years, 5 potential vaccines
  4. Regulatory review • 1-2 years, 1 vaccine
  5. Manufacturing and delivery

Total = 10 years and $500 million

COVID-19 has changed all that. According to Paul Stoffels, Vice Chairman of the Executive Committee and Chief Scientific Officer at Johnson & Johnson:

“If I look at how we work today with the regulators in the world, where normally we have paper processes which take weeks and months to get feedback, today we talk about getting feedback from regulators within the day.”


Vaccine manufacturing costs

The manufacturing costs are high too, as an article in Control Global explains:

“The commonly accepted industry estimate for a single vaccine batch is around $1M / batch in early phase trials. The consequence of a bad batch is either reprocessing or remanufacturing. Reprocessing could mean very little in terms of delays. Remanufacturing, on the other hand, can take additional weeks or months. It is therefore critical to get both the process and associated measurements right.”

The 2011 article explores the manufacture of multivalent vaccines designed to immunise against two or more micro-organisms, but the process is much what most vaccine teams are following, namely:

“The same basic, still-experimental approach: synthesise DNA or RNA, tuck that genetic material into a vaccine and have it build antigens once it’s shot into the body.”

The process has a number of challenges, as the Control Global article explains:

“Hanging load cells were selected because the system is so dependent on accurate measurement and control. Overcoming the dispensing and weighing accuracy challenges were critical to the project’s success. As a result, the selected load cells had the following features:

  • Ability to withstand high lateral forces caused by the “pulling” of the tubing connecting the bags to the process and bracketing assembly and the pulsations associated with the peristaltic pumps;
  • Required accuracy of 0.02% of cells;
  • Readings unaffected by thermal or vibratory interference;
  • Moveable load points to compensate for “shifting” of the bag on the strain gauge, not only as a result of changes in the bag profile, but also the “rocking” assembly used for mixing after weighing.”


Rapid production is key

Producing a vaccine (or vaccines) that can be delivered worldwide in quantities in the billions is a major challenge, as Seth Berkley, CEO of vaccine alliance GAVI explains:

“No pharma company could make five billion doses in the next year or so, but if several of us get to the finish line in the type of timelines I talked about, then we should be able to put a big dent in the spread of the virus.”


Load cells playing their part

It makes us proud to know that the humble load cell is playing its part in this massive global endeavour to immunise the world against COVID-19. If you have a project that requires accurate and reliable data using load cells, call us. We design and manufacture our own high quality load cells here in the UK, with swift delivery times. We can also create bespoke load cell solutions for your project – just call us to discuss.