Temperature plays a key role in molecular dynamics as it can affect the stability of many compounds. The higher the temperature, the more the thermal energy that can increase the chances of chemicalcompositions breaking and more stable ones forming. In the medical world, high temperatures can lead to irreversible changes within compounds found in various medications, thereby reducing their effectiveness.

The same can happen to vaccines as they are biological products that are thermosensitive in nature. If they get exposed to inappropriate temperatures, their active components can degrade, thus diminishing their potency. Once it is lost, the vaccines will not be able to provoke the necessary immune response in the vaccinated patient. It, therefore, becomes critical to keep vaccines protected from temperature variations and to safely store and transport them from the point of manufacture until administration.

Cold chain to the rescue top: preserving the vaccine’s stability

Maintaining a reliable cold chain can ensure the safe storage of vaccines. A vaccine cold chain is a network of medical-grade refrigerators, freezers, and transport solutions designed to always keep the vaccines at the intended temperatures, throughout the distribution process.

However, the requirements for a cold chain can vary greatly depending on the vaccine’s composition. Those that do not contain preservatives – whether lyophilized or liquid – should be stored between +2°C and +8°C during the immunization session. E.g., vaccines for Diphtheria (DT), tetanus (Td) or pertussis are recommended for refrigeration between 2°C and 8°C, while vaccines containing lyophilized varicella are recommended to be stored frozen between -15°C and -25°C.

When considering the recently introduced COVID-19 vaccines, the first ones, developed by Pfizer-BioNTech and Moderna, have shown high efficacy rates and demonstrated strong protection against the SARS-CoV-2 virus.These vaccines are the latest generation of vaccines and utilize messenger RNA (or mRNA) to provoke an immune response in the person being vaccinated. However, to ensure the genetic material used within them remains stable, both the vaccines require ultra-cold storage with the Pfizer vaccine requiring a storage condition going as low as -70 °C. Meanwhile, AstraZeneca, Covishield, and Covaxin require +2°C to +8°C storage whereas the Russian-developed Sputnik V needs storage at temperatures of -18°C or below.

Significance of medical-grade vaccine refrigerators and freezers

Not all refrigerators are designed to store thermosensitive vaccine doses. Medical refrigerators and freezers are designed with reliable cooling technology and superior materials. These provide the necessary temperature uniformity required for secure vaccine storage, usually achieved via a forced or a controlled air-cooling system.However, this might not be the case for household/ non-medical refrigerators. There can be severe temperature excursions inside these products, that can result in vaccines losing their efficacy. The following features that differentiate medical-grade vaccine cold chain products from their non-medical counterparts:

1. Superior temperature control: The cooling technology and design features including the gaskets and insulations, ensures that the temperature is always maintained at the intended temperature range inside the products. These also guarantee a superior hold over and door opening recovery during adverse events and door openings.

2. Safety and Security: The safety features of the products play a critical role in ensuring that even during adverse events, the specimens are not exposed to extreme temperatures. The audio-visual alarm systems are designed in a way to alert the healthcare staff to allow a swift response, thus protecting the integrity of the vaccines. Other security features like door locking mechanisms, access control, etc.will ensure that only authorized personnel are accessing the vaccines.

3. Certifications: The certifications are a testament to the quality of the products and medical-grade refrigerators are associated with globally recognized certifications. Some of these include the WHO PQS, EU MDR, US FDA etc. 1.

4. Real-time monitoring systems: Monitoring the specimens 24/7 adds one more layer of securityfor the vaccine storage. Reliable medical-grade vaccine refrigerators and freezers monitor the vaccines 24/7 and alert the health care workers in case of an anomaly. These systems provide a real-time view of the interior storage temperature, exterior ambient temperature, GPS location,etc, that can be accessed anywhere from the world.

While designing the vaccine cold chain, importance should also be given to factors like availability of reliable electricity, ambient conditions, etc. Availability of reliable power supply can be a challenge when it comes to remote ‘last mile locations. This can be either due to significant voltage fluctuations or long hours of power cuts. Using a vaccine cold chain product with an integrated voltage stabilizer ensures that the voltage spikes in the power supply don’t hamper the functioning of the vaccine cold chain thereby endangering the safe storage of vaccines. However, for locations that lack power supply or face long hours of power cut, Solar Direct Drive (SDD) vaccine refrigerators should be considered. Powered by solar panels, the high-quality SDD products ensure a 24/7 safe storage of vaccines. Some other factors that need to be considered are the ability to offer corrosion resistance and also able to function reliably in tropical conditions.

Significance of medical transport boxes in building a reliable vaccine cold chain infrastructure

As vaccines leave the manufacturer and are delivered to distribution centers, transport boxes are used to move doses from the central hubs to the locations where the vaccines are administered, whether they are large immunization centers in cities, clinics in small towns, or even the last mile immunization campaigns in remote villages. Its commonly observed that there is a tendency to use household transport boxes/ cardboard boxes and picnic cooler boxes for transporting vaccines. However, these arrangements for the transportation of vaccines are not medically recommended as the temperatures vary inside, thereby affecting the vaccine potency. A reliable medical transport solution backed by robust technology can provide long autonomy, high shockresistance, and efficient 24/7 temperature monitoring, ensuring the best vaccine safety even in harsh environments.

Considering that vaccines (including the COVID-19 vaccines) are thermosensitive, it is vital that we focus on developing a reliable vaccine cold chain infrastructure in the country by procuring high-quality medical-grade vaccine refrigerators/ freezers and vaccine boxes. This will safeguard the vaccine potency and ensure the effective distribution of all the doses, especially when highly thermosensitive mRNA vaccines arrivein the coming months.

Mr. Jesal Doshi, Deputy CEO, B Medical Systems

(DISCLAIMER: The views expressed are solely of the author and ETHealthworld.com does not necessarily subscribe to it. ETHealthworld.com shall not be responsible for any damage caused to any person/organisation directly or indirectly.)