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Success Of mRNA Covid-19 Vaccines Is ‘Just A Glimpse Of Their Full Potential’

According to a new Perspective published in the Medical Journal Of Australia, the success of mRNA vaccines against Covid-19 shows “just a glimpse of their full potential.” 

Isabella Overmars is a research coordinator at the Murdoch Children’s Research Institute, and her and her colleagues are responsible for the published Perspective in which they explained why mRNA vaccines are so successful. The mRNA contains a code for a specific antigen that is transferred into a host cell where it is then translated into a coded protein. 

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“This typically leads to the host cell displaying the protein on its surface to promote cell-mediated immunity, and the host cell releases proteins outside of the cell which are taken up and presented by other antigen-presenting cells to promote antibody-mediated immunity,” they wrote.

mRNA vaccines are being held in such high regard for a multitude of reasons, including their low toxicity, and the fact that “there is no possibility for an infection to occur from the vaccine itself”.

“mRNA vaccines do not rely on non or mildly pathogenic viral vectors as a delivery method, which in some cases can cause issues of immune-based clotting disorders, such as thrombosis with thrombocytopenia syndrome (TTS), and antivector immunity,” Overmars wrote.

“The manufacturing process also has several benefits, including in vitro development and use of synthetic materials, which improves manufacturing consistency. Moreover, mRNA vaccines can be rapidly synthesized after the required sequence is known, and modifications can be expedited, which is advantageous in responding to emerging immune-evasive variants.”

The biggest “limitation” to mRNA technology is the fact that it can be easily destroyed, which is why the vaccines need to be stored at cold temperatures.

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“mRNA vaccine development will continue to accelerate, spurred on by the success of SARS-CoV-2 vaccines, and further improvements to the technology may mitigate some of the current limitations and facilitate broader reach.”

“For example, strategies to make the mRNA vaccines self-amplify, meaning the mRNA delivered in the vaccine encodes not only the antigen of interest but also the replication machinery that amplifies the mRNA, will reduce the amount of mRNA needed in each vaccine. Moderna is already in phase 1 with a seasonal influenza quadrivalent product, and is developing other combination vaccines, including one for human metapneumovirus and parainfluenza virus,” wrote Overmars and colleagues.

“Existing challenges need to be addressed to ensure equitable access and expansion. To do this, manufacturing facilities with advanced mRNA technology may be required in multiple locations globally,” they explained. 

“Testing of different additives, adjuvants and delivery mechanisms will be important to increase the stability of mRNA vaccines at higher temperatures and to therefore facilitate equitable access.”

“mRNA technology has progressed rapidly over the past 2 years in response to the global COVID-19 pandemic, revealing new and exciting avenues for prophylactic and therapeutic vaccine development,” they concluded.