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The take-home message is that variants will emerge and we must closely monitor their spread.
Australia has recently seen SARS-CoV-2 (the virus that causes the new coronavirus disease) escape several times from hotel quarantine, including in Brisbane, Perth and Melbourne.
These incidents have been particularly concerning because they involved people infected with “variants” of the virus.
But what exactly are these variants and how concerned should we be?
What is a variant?
Viruses cannot replicate and spread on their own. They need a host and they need to hijack the host’s cells in order to replicate. When they replicate in a host, they face the challenge of duplicating their genetic material. For many viruses, this is not an exact process, and their offspring often contain errors, meaning that they are not exact copies of the original virus.
These errors are called mutations, and viruses with these mutations are called variants. Often these mutations do not affect the biological properties of the virus. That is, they have no effect on how the virus replicates or causes disease.
Read more: Perth is the latest city to suffer a COVID quarantine violation. Why does this keep happening?
Some mutations can affect the ability of the virus to replicate and / or transmit. Variants with such mutations are rapidly lost from the viral population.
Every now and then, however, variants emerge with an advantageous mutation, one that means it is better at replicating, transmitting, and / or evading our immune systems. These variants have a selective advantage (in biological terms, they are more “fit” than other variants) and can quickly become the dominant viral strain.
There is some concern that we are seeing an increasing number of variants with advantageous mutations, contributing to the severity of the COVID-19 pandemic.
Here’s a look at the top three variants that you may have heard of in the media.
The ‘UK variant’ – B.1.1.7
This variant was first detected in the UK in late 2020. It has a large number of mutations, many of which involve the virus’s spike protein, which helps the virus invade human cells.
It has spread rapidly throughout the UK since its inception, and to at least 70 other countries, including Australia.
The fact that it has spread so rapidly and has rapidly replaced other circulating variants suggests that it has some sort of selective advantage over other variants.
After examining the evidence surrounding the new variant, the UK New and Emerging Respiratory Virus Threat Advisory Group (NERVTAG) concluded that it was “moderately confident” that the variant is substantially more infectious than other variants.
This may be the result of one of the mutations in the variant’s peak protein, a mutation called “N501Y.” A pre-printed manuscript, uploaded last month and yet to be peer-reviewed, found that N501Y is associated with increased binding of the virus to a receptor found on the surface of many of our cells, called “ACE2.” This could mean that the variant is even more efficient at entering our cells.
Although the variant was not initially associated with more severe COVID-19 symptoms, more recent data have led NERVTAG to conclude that there is a “realistic chance” that infection with the variant “is associated with an increased risk of death.” compared to non-B. 1.1.7 viruses.
However, the group recognized that there are limitations to the available data, and this remains an evolving situation.
The ‘South African variant’ – B.1.351
This variant was first detected in Nelson Mandela Bay, South Africa, in October 2020. Since then it has been found in more than 30 countries.
Similar to the UK variant, it quickly outperformed other SARS-CoV-2 variants in South Africa. It now represents more than 90 percent of the SARS-CoV-2 samples in South Africa that undergo genetic sequencing.
Like the UK variant, it also has the N501Y mutation in the spike protein, meaning it is more efficient in gaining access to our cells to replicate. This can help explain its rapid spread.
It also contains several other worrisome mutations. Two of these, called “E484K” and “K417N,” are bad news for our immune systems. They can reduce how well our antibodies bind to the virus (although this is also based on pre-printed data awaiting peer review).
But there is no evidence yet to suggest that the South African variant is more deadly than the original variants.
The ‘Brazilian variant’ – P.1
This variant was first detected in Japan in a group of Brazilian travelers in January 2021.
It is now very prevalent in the Brazilian state of Amazonas and has been detected in countries such as South Korea and the United States.
Like the South African variant, the Brazilian variant has the spike protein mutations N501Y, E484K, and K417N (as well as many other mutations).
While there is no evidence that this variant causes a more serious illness, there are concerns that it has facilitated a wave of reinfections in Manaus, the largest city in Amazonas, which was thought to have achieved “herd immunity” in October. last year.
What does this mean for vaccines?
Major vaccine developers are testing the efficacy of their vaccines against these and other variants. Generally, currently licensed vaccines protect relatively well against the UK variant.
But recent phase 2/3 data from Novavax and Johnson & Johnson suggests reduced protection against the South African variant. The Oxford / AstraZeneca Vaccine Group also released data over the weekend suggesting that their vaccine offers only minimal protection against mild-to-moderate disease caused by this variant.
Read more: South Africa has halted the launch of AstraZeneca’s COVID vaccine, but it’s too early to say Australia should do the same
However, it is important to recognize that reduced protection does not mean that there is no protection at all, and that the data is still emerging.
In addition, numerous vaccine manufacturers are investigating whether adjustments to vaccines can improve their performance against emerging variants.
The take-home message is that variants will emerge and we must closely monitor their spread. However, there is every indication that we will be able to adapt our vaccine strategies to protect against these and future variants.
Kirsty Short, Senior Lecturer, The University of Queensland
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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