How Vacuum Technology Makes Vaccine Manufacturing Possible
The COVID-19 pandemic has put vaccines in the spotlight, and the public is increasingly interested in how vaccines are manufactured, stored and transported. This article explores how vacuum technology has made COVID-19 vaccines possible at every step of this process. We start by looking at how vacuum is used in vaccine purification.
1. VACCINE PURIFICATION
Purification within the vaccine manufacturing process is paramount and an ultra fast speed centrifuge is used to facilitate this step. The different sedimentation coefficients or buoyancy density of the components within the mixture allow to achieve the purification process.
High rotational speeds of over 30,000 RPM are required to produce complete separation of active species and unwanted contaminants. Such high rotational speeds cause friction of the air within the mixture and result in the generation of heat. This can damage the active components. To counteract this, high vacuum pump systems that incorporate a turbomolecular pump (TMP), and ideally a dry vacuum pump, are used to extract heat from the mixture.
2. DRYING AND FREEZING STORAGE VACCINES
Active microorganisms and enzymes are the key components of vaccines. Lyophilization is used to ensure that these components are protected and that the vaccine remains effective.
The freeze-drying process involves mixing the finished live vaccine with a water-based stabilizer to form a suspension, which is then frozen. Then a vacuum is applied with a little heat so that the ice sublimates from solid to vapor. Due to the low temperature of the sublimation process, the vaccine components remain active and undamaged.
The lyophilized vaccine can be sealed and stored under vacuum; This has the advantages of offering long pot life, rapid dilution with diluent during use, and unchanged recovery characteristics. Vacuum storage is currently the most common method of preserving live vaccines.
3. PRODUCTION OF GLASS VIALS FOR VACCINES
Before transportation and distribution, the vaccine is distributed in glass vials. The correct choice of glass is crucial to maintain the efficacy of the vaccine; Only low borosilicate glass has the chemical stability necessary for long-term preservation of the vaccine. In addition, this glass has excellent stability to thermal expansion and contraction, which is important for storage at temperatures below ambient.
Vacuum is required in two stages of borosilicate vial production:
- Vacuum is used during the melting process to remove trapped air in the glass and generally works at a pressure of around 50 mbar. Glass dust and high temperatures are issues that need to be addressed as well. Liquid ring pumps have traditionally been used. But more and more rotary vane and screw oil pumps are being used to reduce operating costs. Dry screw pumps offer an oil-free alternative.
- The molding process requires vacuum levels of around 100 mbar. Short pump downtimes and continuous operation are essential. Oil rotary vane pumps, screw pumps and dry screw pumps are increasingly being used.
4. TRANSPORTATION AND STORAGE OF VACCINES
Vacuum Isolation Panel (VIP) technology is critical for the transportation of COVID-19 vaccines. For example, the Pfizer BioNTech vaccine requires storage at -60°C. Maintaining this temperature presents a significant challenge.
VIPs offer a method of maintaining these temperatures in an energy efficient way. VIP offers very low thermal conductivity of 0.004W (mK), with a typical vessel wall thickness of 25 - 60mm. In comparison, conventional 150mm thick mineral wool would have a value of 0.04 W (mK).
This leads to higher efficiency and more storage within the refrigeration unit.
The structure of VIP consists of three parts: insulating material, a gas adsorbing material (Getter) and a closed insulating film (barrier). This closed insulating barrier is pumped to a high level of vacuum prior to sealing, thus offering exceptional insulation properties.
The front high speed vacuum pump train minimizes the time before the diffusion pump kicks in, for quick turn of the panels.
Source: Vacuum Science World