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Viral Mutations and Implications for COVID-19 Vaccines

Covid-19 pandemic

The world is still reeling from the impact of the novel coronavirus (SARS-CoV2) which has caused over a million deaths globally, with millions more infected.

The economic consequences of COVID-19 have been just as severe. Many countries have shut down entire industries, millions of people have been laid off from their jobs and are unable to cater for themselves and their families. Trading within and between nations has slowed down to a trickle although things are beginning to pick up.

Some experts opine that it would take a few years for the world to fully recover from the economic and social effects of the pandemic. There is indeed a good chance that some aspects of the society may have been altered forever.

As the death toll from COVID-19 rose however,so did the resolve of researchers and health professionals around the world. They were, and are still searching for the quickest and safest solutions to this public health nightmare we are experiencing.

Several pharmaceutical drug candidates have been trialled and proposed as solutions, with varying degrees of success. The race for an effective and safe vaccine was started as soon as scientists determined the sequence of the genetic material of the virus.

Months later, through sheer hard work and innovative thinking, a few vaccine candidates have already been rolled out and countries have begun the process of vaccinating millions of citizens against SARS-CoV2.

It did not take very long for reports of new strains of the coronavirus to emerge, forcing researchers and pharmaceutical companies to examine the potencies of currently available vaccines against the new strains discovered in the United Kingdom, Brazil and South Africa.

Let us briefly shed some light on how viruses mutate.

Viruses broadly fall under two categories, namely: DNA viruses and RNA viruses.

DNA viruses have a piece of DNA as the store of their genetic information while RNA viruses have RNA as their genetic material.

When a virus invades a host cell, it hijacks the cell's machinery to replicate its genetic material many times over and produce viral proteins. These proteins are then packaged into millions of new copies of the virus in a very short period of time.

The process of replicating the genetic material of the virus is prone to error and these errors introduce changes or mutations in the sequence of the viral genetic material, be it DNA or RNA.

The scientists studying viral mutations have observed that RNA viruses mutate at a much faster rate than DNA viruses. Rafael Sanjuan et al. 2016, suggest that viral genetic diversity as a result of mutations is determined by processes that are virus-dependent as well as host-dependent. Read the article here

Should we worry about viral mutations?

As mutations occur in the genetic material of a virus, modified versions of the original viral proteins are produced, leading to slight differences in the structure and sometimes in the functions of parts of the virus. These differences may impact the treatment measures deployed against the virus. For example, a significant mutation in the spike protein of a virus might enable the virus to evade antibodies which were generated against an earlier strain of that virus.

While some mutations might be beneficial to the survival of a virus, for instance, by making it more easily transmissible, some mutations may indeed hamper the ability of a virus to readily infect new hosts or cause severe disease in infected hosts. Scientists have observed multiple changes in the spike protein of the South African variant of the coronavirus, which allow the virus to bind more tightly to the ACE2 receptor on human cells and enter the cells more efficiently. Read the article here.

Implications for COVID-19 vaccines

COVID-19 vaccination

As we try to keep up with new strains of the coronavirus emerging from different countries in the world, it is obvious that we just cannot develope vaccines to target every possible strain of the virus. The good news is that we may not need to account for every possible mutation in the spike protein of the coronavirus, as studies have shown that the antibodies produced in response to vaccination are able to identify and bind effectively to a significant number of the mutated viral strains.

In fact, both Moderna and Pfizer recently assured the public that their mRNA vaccines remain effective against the newer strains of the coronavirus.

One thing is clear : we will become equipped to deal with the virus as we learn more about it. In the meantime, it is imperative that we do our very best not to contribute to the transmission of this virus by maintaining good hygiene, staying relatively isolated when sick, maintaining social distancing when out in the open as much as possible, and of course wearing our face masks.

We shall overcome!


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