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With COVID-19 pandemic slowly turned into an endemic, laypeople nowadays are familiar with different types of vaccines. Few months into the pandemic, researchers around the world were racing to find an effective vaccine to combat SARS CoV-2 infection. Not only following an established route in vaccine development, some researchers went through different pathways to develop vaccine. One of them was a small Biotech company in Germany called BioNTech who came up with an idea to develop an mRNA-based vaccine.
Why did they develop mRNA-based vaccine in the first place? Why did they not instead develop a vaccine made of the weakened virus which have been proven effective for other diseases? First of all, mRNA-based vaccine was not totally a novel thing in biomedical science field. The first successful mRNA transfer to mouse cells was performed as early as in 1990. Unfortunately, since then there had been no significant improvements in mRNA vaccines due to concerns on mRNA instability, innate immunogenicity, as well as inefficient delivery methods.
Only in the past few years, with the advancement of mRNA technology, researchers started to consider mRNA vaccines as the future solution to encounter various infectious diseases. mRNA vaccines can be delivered with special vehicles that maintain its stability. Therefore, the vaccine will not be degraded once it enters human host. One of the advantages of an mRNA-based vaccine is that once it is inside the host, it reaches ribosomes, incorporated in the gene translation machinery, and directly translated into proteins. These proteins will then be recognized by the host immune system and teach this immune system to develop a defence mechanism against this specific part of the pathogen. In the case of SARS CoV-2, the mRNA-based vaccines contain mRNA of spike protein. Therefore, our immune system will be trained to recognize and eventually create a protection against this specific protein of SARS CoV-2.
From the description above, there are many benefits for considering mRNA vaccines as a solution for various diseases. First, the production cost of mRNA vaccines is relatively cheaper compared to other types of vaccines. Second, the delivery process is safe as mRNA is a harmless tiny genetic material of a virus. Third, it quickly triggers the host immune response as the mRNA can directly be translated into protein. With all of those potential, why did most people sceptical with the release of an mRNA-based vaccine to control the spread of COVID-19? The answer is because of inconsistent results from the clinical trials and this kind of vaccine has never been known before to counter any infectious diseases. In terms of logistic, this vaccine needs to be stored in -70°C. This found to be difficult when it needs to be distributed to less-developed countries, such as African and some rural Asian countries.
Nevertheless, mRNA-based vaccine is one of the earliest vaccines that was being approved by WHO. Is it totally safe? This remains a question difficult to answer. Apart of its relatively mild side effects in most healthy people, recent studies have reported serious effects of this vaccine in immunocompromised people. The administration of mRNA-based vaccines to those people triggered the activation of humoral immune response due to neutralizing antibodies production. This event is coupled with pro-inflammatory CD4+ and CD8+ T cells activation and Th1 cytokines production. This is a threatening condition especially in people with autoimmune diseases, because the over-reactive immune response might further deteriorate their health conditions.
The current solution for immunocompromised people to be protected from COVID-19 is to recommend other types of vaccine. However, ideally all types of vaccines that are available in the market should be able to accommodate all people – no exceptions. This is a challenge for future vaccine developments. The development of an mRNA-based COVID-19 vaccine was a great innovation in medical field. Next, vaccine researchers perhaps need to think about how to improve the vaccine delivery method so that it will be safe for the immunocompromised patients. This obstacle should not discourage us to vaccinate ourselves against COVID-19. On the other hand, we must always show our full supports for the improvement of vaccine development. Not only for COVID-19, but also for future pandemics.
Anand, P., Stahel, V.P. The safety of Covid-19 mRNA vaccines: a review. Patient Saf Surg 15, 20 (2021). https://doi.org/10.1186/s13037-021-00291-9
Pardi, N., Hogan, M., Porter, F. et al. mRNA vaccines — a new era in vaccinology. Nat Rev Drug Discov 17, 261–279 (2018). https://doi.org/10.1038/nrd.2017.243
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