Amidst rising cases of the Omicron variant, and questions over new forms of the virus and vaccine effectiveness, Biosciences student Summer takes a deeper look at the science behind both, and how the pandemic could unfold going forward.
By Summer Revely
With COVID-19’s outer structure under constant rapid evolution as infection spreads between hosts, we must be vaccinated to level off the ‘tidal wave’ that comes as new variants appear. But this is easier said than done.
Coronaviruses are a wide viral family that have previously caused the SARS and MERS epidemics of the early 21st Century. Progression of the spread and attempts to produce a vaccine at these times, especially during the SARS outbreak of 2002-2004, showed to the world how beneficial a coronavirus vaccine could be in terms of reducing mortality with coronavirus infections.
We were aware of the possibility of a coronavirus pandemic, and the need for a coronavirus vaccine as a result, but we were yet to produce a highly modifiable one to protect against other members of the coronavirus family successfully. The COVID-19 pandemic may just have been the straw that broke the camel’s back, but synergically what has pushed for a very necessary, effective coronavirus vaccine.
We are still unsure of the exact pathways that COVID-19 takes to give rise to the varied symptoms seen. However, studies show that the virus promotes inflammation, vascular leakage in the respiratory system, and clotting of blood cells so that more platelets are present. All these pathways shorten the space between alveoli in the lungs and endothelial cells in blood vessels by clogging it in various ways. This shrinks the space at which gas exchange can happen in the lungs, and therefore gives reason for how sufferers are quite often breathless, as sufficient oxygen cannot be absorbed from the bloodstream.
COVID-19 is a particularly dangerous coronavirus because of how quickly it can replicate and spread between hosts. Spontaneous mutation that arises in viral DNA replication is what gives rise to new COVID variants; these cause changes to the viral outer structure, and as a result change the way in which they can bind to host cells and enter them to further spread infection. This binding is achieved by interaction between viral surface proteins and specific receptors on host cell surfaces.
To be an effective vaccine, one must therefore predict and protect the host against as many new variants as possible, so that these host cells cannot be penetrated and infected with viral DNA. Or at least be protective enough so that if a host does become infected, an immune response is activated to alleviate any life-threatening symptoms. Both factors are the ultimate aims of the scientists working worldwide to tackle the COVID-19 pandemic with vaccines.
Currently, widely used COVID-19 vaccines differ in their mechanism of function, what makes them particularly advantageous, and consequently their possible efficacy in protecting against variants that may appear in the future.
Early in the global ‘vaccine race’, the Novavax vaccine seemed promising. It works similar to the Hepatitis B vaccine, by using subunits of the virus’ surface to fix the immune system upon the coronavirus target, so that it can be fought. However, the fact that this method cannot give rise to as strong of an immune response as other techniques, and that it requires other substances to induce long-lasting immunity makes it less effective.
Like the vaccines previously produced against Ebola, the University of Oxford & AstraZeneca, and Johnson & Johnson vaccines against COVID-19, modify harmless viral DNA to incorporate that of COVID, so that this can be injected into the host and build immunity without giving rise to COVID symptoms. Using a live vector here is potentially more effective than dead, dormant or subunit viral forms, as the immune response produced is stronger.
Alternatively, both the Pfizer and Moderna vaccines use an administration approach that is yet to be done successfully. The theory is that the insertion of modified RNA molecules can be used to teach the immune system to target and stop the production of proteins that are important for coronaviruses – and hopefully other viruses – to sustain life. An effective, modifiable vaccine of this kind could be very helpful medicinally in the future against other pathogens too. The fact that these RNA sequences can be so conveniently modified at rapid speeds with modern technology provides hope that Pfizer and Moderna could modify their vaccines quickly and selectively (perhaps similarly to how a new flu jab is produced yearly) against new variants that appear.
Whilst science looks promising of the idea that the current vaccines are the solution to the pandemic, the ever-evolving COVID-19 virus continues to fight back. Only time will tell, but we can have hope that with slight tweaks over time, current vaccines can overcome COVID-19, and possibly other coronaviruses to come.
Thank you for reading!
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