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Recently Pfizer’s vaccine has been in the news for needing to be stored below 0oC. The development of such a vaccine becomes even more problematic for countries that are in the low and middle-income (LMIC) bracket such as India. Why do you ask? Because we simply cannot create a supply chain that can tackle the distribution of these vaccines in the far and wide regions in this humungous country! 25% of vaccines that are transported through such chains degrade before reaching their destination. So, This is why ‘warm vaccines’ seem to be the answer to this problem. Now that we are getting closer to getting a vaccine for COVID-19, they’re becoming even more relevant with time. So, what are warm vaccines?

Warm Vaccines

Warm vaccines are vaccines that can withstand normal temperatures and do not need to be stored in ice. When any vaccine is stored or shipped anywhere, they need to be done so by maintaining their temperatures between 2o to 8o C. Even the current COVID-19 vaccines that are in the development process are ‘cold vaccines’ which can be a huge impediment considering the current supply chain that we have.

Warm vaccines are also known as heat-stable vaccines and they can be stored at different temperature ranges for different periods of time. This is fairly simple considering that the lower the temperature, the higher the amount of time it does not need to be stored in a cold room/ container. The temperature ranges given below are of the current COVID-19 vaccines that are under development.

  • 100o C for 90 minutes
  • 70o C for 16 hours
  • 37o C for over a month

To date, only three vaccines have been improved for implementation in healthcare programs by the World Health Organization (WHO). They are vaccines for Meningitis, Human Papillomavirus Virus (HPV) which is known to cause cervical cancer, and Cholera. All these have made a huge impact in healthcare systems especially those in under-developed and developing tropical countries where storage and distribution to remote areas are incredibly difficult. Let’s see how this impact was made.

Broken Healthcare Supply Chain

In countries such as India, we already have a very extensive network for our vaccine distribution projects because of the number of people that need access to it. Most of the vaccines that we have today are being stored between 2 to 8o Celsius and they’re done so using the equipment mentioned above. But all this requires a huge amount of resources and trained professionals to carry out this process. Especially in LMIC countries, this might not be feasible due to the lack of resources such as funding and a skilled workforce!

The current cold chain process (Source: WHO). The ones marked in green are the main turning points where vaccines can become compromised in the process. While in R&D, the vaccine can be formulated to be stored at a more suitable temperature, if it gets approved for cold storage, there is a high chance that it could degrade in the forthcoming steps.
The current cold chain process (Source: WHO). The ones marked in green are the main turning points where vaccines can become compromised in the process. While in R&D, the vaccine can be formulated to be stored at a more suitable temperature, if it gets approved for cold storage, there is a high chance that it could degrade in the forthcoming steps.

Another issue that has been recently identified is the need for an alternative to needle vaccines. Why do we need this? The answer is fairly simple, really. With a needle vaccine, it is quite fearsome for some people, to say the least. It has also been identified to be one of the reasons why some people just refuse a vaccine.

In terms of transportation, these are the major points for lapse in vaccine handling. Light yellow - Low risk; Orange yellow - Medium risk; Red - High risk (Source: International Air Transport Association - IATA)
In terms of transportation, these are the major points for lapse in vaccine handling. Light yellow – Low risk; Orange yellow – Medium risk; Red – High risk (Source: International Air Transport Association – IATA)

Pressure is already mounting by anti-vaxxers in different regions of the world. It’s needless to say having an alternative that can be inhaled or ingested would be a much better option. They would not need to have a trained professional administer such a vaccine, nor would we have any degradation issues with transport!

Warm vaccines under development

Right now in the context of COVID-19, there are a few vaccines that are being tested so that they can survive the cold chain. One prime factor in the development of mRNA vaccines (such as in the case of Moderna & Pfizer) is that most developing countries do not have the means to manufacture such a high-end pharmaceutical product. This means that this will have to be flown in from another country which elongates the process further. In India, right now there is a vaccine being worked upon by Dr. Raghavan Vadarajan’s group at the Indian Institute of Science (IISC).

Schematic representation of the selection logistics of the protein and protein segment. It shows an animated figure of the 2019 novel coronavirus. Segment presented in green cartoon refers to the receptor binding domain (RBD) of the spike protein.
The representation of the RBD in the SARS-COV-2 virus (Source: https://doi.org/10.1101/2020.05.31.126615)

In this case, they have developed a vaccine that specifically targets the receptor binding domain (RBD) of the virus. Too complicating? Let’s break it down. We all know that coronaviruses have a unique spike like structure on their surface and these spike essentially help in their attachment to the host cell (humans, in this case).

From studies done on related coronaviruses, they have figured out that this domain specifically is heavily targeted by antibodies in our body that help in fighting them off and neutralizing them. By engineering such vaccines with an RBD domain, the antibodies would naturally be produced in our body and can mount a protective response in case of coming in contact with the virus! The manuscript can be read here. While they have successfully managed to immunize guinea pigs, they’re waiting on approvals for Phase III trials at the moment.

What can we expect in the near future?

While Pfizer’s & BioNTech’s vaccine is due to be implemented on a mass scale tomorrow (7th December 2020) in the UK, we in India still hope that a thermotolerant and immunogenic vaccine can be produced because that would be a huge win not only for us, but many other countries in the world. These would be particularly useful in countries where air transport or even road transport is not easily accessible due to weather and terrain. Here’s to hoping that such a vaccine candidate is approved after the right safety and efficacy trials in the near future!

References

Raghavan Vadarajan & Group (2020, August 16). Design of a highly thermotolerant, immunogenic SARS-CoV-2 spike fragment. Retrieved from https://www.biorxiv.org/content/10.1101/2020.08.15.252437v1.full.pdf

Biswas, S. (2020, November 6). Covid-19: How a ‘warm vaccine’ could help India tackle coronavirus. Retrieved from https://www.bbc.com/news/world-asia-india-54792287

Grover, N. & Safi, S. (2020, November 20). Scientists race to find ‘warm’ Covid vaccine to solve issue of cold storage. Retrieved from https://www.theguardian.com/global-development/2020/nov/20/scientists-race-to-find-warm-covid-vaccine-to-solve-issue-of-cold-storage

Vaccine storage and handling (2020). Retrieved from https://www.paho.org/immunization/toolkit/resources/partner-pubs/ebook/Chapter5-Vaccine-Storage-and-Handling.pdf?ua=1

The vaccine cold chain (2020). Retrieved from https://www.who.int/immunization/documents/IIP2015_Module2.pdf

Nagurney, A. (2020, October 5). The Challenges of Vaccine Cold-Chain Distribution Must Be Met to End the Pandemic. Retrieved from https://globalbiodefense.com/2020/10/05/the-challenges-of-vaccine-cold-chain-distribution-must-be-met-to-end-the-pandemic/

P. S.: Curious to learn about a recent development in the field of HIV? Learn more about elite controllers - people who are immune to HIV! The article has even been mentioned by popular science blog aggregator - ScienceSeeker. Click here to know more!

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