As the majority of the U.K. was plunged back into the lonely and stagnant lifestyle of a national lockdown, many questioned exactly how long this oscillation of freedom and restriction would continue…
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Pandemics end in three principle ways. The first is through containment; keeping an infection geographically isolated, however with regards to COVID-19 I think we can all agree that this ship has sailed. The second scenario unfolds through a change in public perception, as the infection shifts from pandemic to endemic. COVID-19’s high infection and mortality rates again makes this unviable. The final route is herd immunity, achieved either through mass exposure, or more preferably, through mass vaccination.
The ground-breaking news delivered by Pfizer-BioNTech on the 9th November provided both a potential answer to the question, “when will it all blow over”, along with a new statistic of which I am sure was mentioned in every COVID-related conversation this week: “the vaccine is 90% effective”.
Everyone is holding their breath as the data is finalised and approval is gained, however the fact this vaccine actually works isn’t the only reason it’s so exciting. The vaccine is a naked DNA vaccine. More specifically, an mRNA vaccine, and the first of its kind. If successful, Pfizer-BioNtech may have paved the way to a new era of vaccine research and development, arming the world against future pandemics which are certain to follow.
This vaccine is different to the traditional types of vaccination upon which we have relied to triumph against past infectious diseases. These include inactivated vaccines, which contain dead versions of the pathogen (a microorganism which causes disease), attenuated vaccines, (the type responsible for wiping out smallpox), and sub-unit vaccines, which contain small fragments of the pathogen. All three types react with cells in the immune system and trigger both an immune response and protection.
Pfizer-BioNTech’s approach focuses instead on the genetic material which codes for the manufacture of a part of the virus. To understand how this generates immunity, we need to brush up on some basic biology.
DNA is present in every cell. It contains information to build every single protein found within that organism, similar to an instruction manual. When the cell requires a certain protein, it will find the relevant segment of DNA which codes for that protein and make a “copy” called mRNA (messenger RNA). The mRNA is then read by the cell’s protein production mechanism, which creates the protein.
If, therefore, the cell’s protein production mechanism was given a different piece of mRNA, for example mRNA originating from COVID-19, the cell would begin to construct COVID-19 proteins.
This is the basis of the Pfizer-BioNTech vaccine. The piece of mRNA present in the vaccine encodes a COVID-19 “spike” protein, which helps the virus dock with and enter our cells. Once the vaccine is administered, our cells read the “spike” protein mRNA, create the protein and place it on the cell surface where it is then recognised by our immune system, creating an immune response. Antibodies are produced, which bind to the identical “spike” protein found on all COVID-19 particles, preventing the virus from entering our cells whilst simultaneously flagging the viral particles for uptake and destruction by other cells of the immune system such as phagocytes. We have now established protection.
Although this sounds straightforward, the main hurdles in development have always been found in delivering mRNA into human cells. Simply injecting genetic material into the human body doesn’t work, as the material is unstable and so will break down. Even if stable, the cells’ fatty membrane prevents genetic material from entering the cell. Pfizer-BioNtech have bypassed this problem by creating a lipid nanoparticle, which carries the COVID-19 mRNA into the cell.
Vaccines of this type take months, not decades to research and produce. As soon as a relevant pathogen is “decoded” (that is, its genetic makeup has been revealed), vaccine candidates can quickly be produced.
Expectedly, this breakthrough has raised tremendous hope, however it is important to remember that we are by no means out of the woods. Firstly, the lab results don’t show how long the resulting immune protection lasts. If it is a matter of months as suggested in some studies, many boosters would be required to maintain immunity. Furthermore, we are yet to find if the elderly, those who are most at risk, will demonstrate the strong response required for effective protection.
It’s also worth mentioning that this breakthrough was announced during a press conference, not in a medical journal in which peers would normally review the work.
The vaccine is also unstable at room temperatures, and therefore it must be stored at -70°C. Distributing the vaccine to remote areas will therefore be difficult, particularly in less economically developed countries. Those struggling most will have the least access to the vaccine; an unfortunate yet common theme in the treatment of disease. Fortunately, other potential mRNA vaccines being developed by Moderna and AstraZenica require less extreme temperatures for storage. Due to their practicalities, these vaccines may yet clinch the race for first to the market.
Finally, people’s perspectives must change in order for the vaccine to be effective in wiping out COVID-19. A survey of 70,000 people carried out by University College London found that only 49% would be sure to get a vaccine, regardless of vaccine type. One fifth would strongly refuse, and one quarter believed vaccinations were simply a product of pharmaceutical profiteering. If these statistics are replicated in actual vaccination rate, the virus could remain in circulation for many years.
As vaccination is the fastest way out of this mess, it is crucial that these figures change. It is a tried and tested method, which has allowed us to overcome a host of infectious diseases in the past including polio, smallpox, and rubella. Of course, pharmaceutical companies will make a profit from the successful placement of a vaccine on the market, but without potential profit there is no drive for investment into the costly process of research and development. And yes, it is true, there are small risks associated with vaccination. But these risks are negligible in comparison to the impact that a mass vaccination programme will have on society.
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