Coronavirus mutation keeps moving the goal posts
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Covid-19 continues to keep scientists on their toes with its unpredictable mutation patterns.
Months after the detection of the Delta variant, the deadliest version of the virus yet, another variant, C.1.2, has recently been detected in South Africa and several other countries.
In March, this year, the World Health Organization (WHO) indicated that when a virus is widely circulating in a population and causing a spike in infections, there is a great chance of it mutating and spiking the infection rate.
According to virologist Dr Bonolo Mashishi, viruses are creatures of evolution. They constantly change with time in an attempt to adapt to their environment, in order to not die out.
“A virus changes during the stage of viral replication, as it makes copies of itself. They (viruses) change and adapt to various stimuli to survive and thrive. These stimuli are referred to as, selection pressures. Such selection pressures may be triggered naturally or in response to external triggers (e.g. immune response) that have the potential to limit the survival of the virus.”
Although viruses mutate as a response to trigger their survival mode, there is no specific time frame as to when the mutation would be triggered. The process varies based on the different types of viruses. A virus may mutate several times, thus explaining why Covid-19 has mutated at least three times in the last 18 months, with every variant becoming stronger and deadlier than the previous.
However, Mashishi said variants should not be regarded as “new”. They are still the same virus, with the only difference being, that their genetic make-up, has been modified.
“Genetically, variants are largely similar to the original virus. However, they have diversified from the original or parent virus through an accumulation of mutations in key areas of viral RNA or DNA,” Mashishi explained.
The downside of these multiple variants is the possibility that, as they mutate, they may compromise the efficacy of the available vaccines.
“Some of the changes or mutations seen in viral variants may alter the behaviour of a virus. One such behaviour is the ability of a virus to escape immune responses induced by a vaccine.
“Some SARS-CoV-2 variants have been experimentally associated with the presence of immune escape mutations, however, despite this evidence, vaccines have been found (to be) efficacious in protecting against severe forms of disease, hospitalisation, and death,” said Mashishi.
Given the possibility of viruses escaping immunity responses from vaccination, the WHO said it tracks mutations and variants to monitor and understand how these variants may affect the effectiveness of vaccines.
For the government to minimise the spread of the coronavirus and enable South Africans to equip their immune system to fight off the virus, millions of people need to be vaccinated, otherwise, Charles Darwin’s theory - survival of the fittest would be put to the test.
“Some variants thrive and survive better than others under certain conditions, particularly, those that offer survival advantages, such as ease of spread. The status quo is very fluid and influenced by several factors, such as our immune system. The other important factor is related to the virus. A variant may die out or continue to thrive, if conditions are conducive,” added Mashishi.
What is cause for concern, currently, is that there are many challenges brought about by the emergence of these “new” variants, as they affect factors such as ease of spread between people, increased infection rates, and an increase in the death-rate.
In resource-constrained countries, such as, South Africa, where the continuous detection of new variants steadily puts a strain on the available healthcare facilities and other resources, medical experts recommend that vaccination continues to be prioritised, as more variants will arise in areas where the virus continues to spread from person to person.