Wudan Yan, a freelance journalist, elegantly explains this in his New York Magazine Intelligentsia on 17th February 2021.  

In December 2020, as quickly as excitement grew over the new COVID-19 vaccines that have been approved for use, worry took over.

Evidence worldwide suggested that SARS-CoV-2, the virus that causes COVID-19, was mutating.

P1, a variant first discovered in Brazil, ravaged the Amazonian city of Manaus. 

B.1.1.7 first identified in the United Kingdom, was thought to transmit more readily and, within a matter of weeks, led to a surge in cases and became the dominant strain here in Britain.

B1.351 found in South Africa became worrying because researches found it was able to avoid some of the newest vaccines.  

Viruses mutate all the time and usually mutate to become more transmissible.  New research showed that the SARS-CoV-2 could evolve to not only be more transmissible but also more lethal. 

Over the last year, the virus has already shape shifted multiple times, which raised the possibility that COVID-19 vaccines may have to be updated frequently, similar to how flu vaccines change every year to account for the new circulating strains.

This sounds like bad news, but these vaccines can actually be readily updated, especially the ones developed by Moderna and Pfizer, which are based on mRNA technology.  

As scientists studied the potential use of mRNA vaccines over the last decade, they hope that this cutting edge technology could be used rapidly in emerging pandemics. 

 MRNA vaccines train our bodies to develop an immune response to a segment of a pathogen.  For the COVID-19 vaccines, the mRNA segment codes for a portion of the spike protein, a region of SARS-CoV-2 that helps the virus enter ourselves. After getting vaccinated, our body turns the message into a protein so our immune system mounts and immune response to the protein – similar to what would have happened if we were exposed to the full virus.  

The message portion of these vaccines can be tweaked as the virus mutates.  Scientists can take this mRNA sequence of the new strains and swap it in to produce new vaccines.  

In other words, it is a pretty simple process from a scientific perspective to update these vaccines.  Pfizer and Moderna are already working on updates to the original vaccines to account for the variants.  Pfizer is hoping that this will be available in as fast as 60 days.  

COVID-19 vaccines not based on MRNA but DNA can also be updated by swapping out the genetic material for the sequence of the updated variants.  The issue here is that the DNA based vaccines are surrounded by another virus, called the adenovirus, which helps the vaccine gets inside cells to elicit an immune response. 

Researchers are concerned about multiple shots of these adenovirus vaccines.  The question here is that if you repeatedly immunise patients with these vaccines-it is possible that they can build up an immunity against the carrier vector itself.  

It is also thought that it is possible to combine different vaccines.  For instance, if one gets an adenovirus vaccine and then as the virus mutates gets booster vaccines made from the mRNA.

The question here is whether clinical trials will be required for these new vaccines.  

However, flu vaccines are updated regularly without undergoing clinical trials because the only thing that changes are the strains being targeted.  All other parts of the formulations remain the same. 

It is felt that in the future there could just be a single shot with multiple mRNAs that targets multiple variants.  Researchers have shown that it is possible to put up to 20 different mRNAs into a vaccine and still get a good immune response to all 20 targets.  

It is clear that COVID-19 like all other viruses will continue to mutate.  However, the good news is that the vaccines can be rapidly updated as mRNA vaccines will lead the fight in not only COVID but other infectious diseases.

Essentially, the mRNA vaccines inject a piece of the Coronavirus’ genetic information, the mRNA. That then turns inside our bodies into a complex molecule, specifically a portion of the virus’ protein for spike. Our bodies then learn to mount an immune response to this protein as if we had been exposed to the full virus.  The mRNA segments can be easily swapped with different mRNA variations.

Dr Paul Ettlinger

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