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In December, the UK reported a worrying variant of Covid-19, commonly known as variant B117, which appeared to be more transmissible. Since then, scientists have established that B117 is between 50% and 70% more transmissible than other variants. If more people fall ill there is more pressure on health systems, and in the UK health services are so overburdened that a nationwide lockdown has been imposed.
While many scientists say B117 does not appear to be deadlier, researchers at the UK government’s New and Emerging Respiratory Virus Threats Advisory Group have found that it could increase the death rate by 30% to 40%, although their sample size is small and they declared it necessary. Since B117 is now detected in more than 50 countries, it is urgent to understand the variant.
But other worrying variants have also been identified, particularly in California, South Africa and Brazil.
So what is a variant, and how many are there? And why are some variants of greater concern than others?
Associate Professor at the University of New South Wales, Stuart Turville, who works with the Immunovirology and Pathogenesis Program at the Kirby Institute, says that although many people have referred to some of these variants as new “strains” of the virus, it is more accurate to say that the viral strain that causes Covid-19, known as SARS-CoV-2 , has thousands of variants, which can also be described as subtypes, isolates or lineages.
However, some of these variants have more changes in their genetic instructions, known as the genome, than others. Turville says the Covid-19 genome is about 30,000 base pairs. Base pairs are the molecules on opposite strands of the virus’s genetic material, which form chemical bonds with each other. These chemical bonds act like rungs in a ladder and help hold the strands together.
‘In the context of the variant identified in the United Kingdom [B117], there are about 24 changes among those 30,000, so if you look at that in the context of the whole genome of the virus, it’s not a huge change from where it started in 2020 ” , said Turville. However, this is still a higher number of changes than usual; other variants only have one or two changes, also called mutations, in the genome.
The variant identified in South Africa, called B1351, also has an unusually high number of mutations, including some of those seen in B117. Again, there is no evidence to suggest that this variant increases the severity of the disease, but it has become the dominant variant in Zambia and is therefore likely more transmissible, although investigations are ongoing.
“There have been thousands of different variations,” Turville told Guardian Australia.
“One of the things virologists and molecular virologists are saying is that it’s easier to break something than to turn it into something bigger, better, and faster. There are many variations of viruses that have followed one another. If you remove a key item, it collapses and it’s actually a very fragile virus.
“The key mutants we are talking about are those who survive change and keep going. They’re the ones that started to invade variants in the past, and that’s what we’re seeing right now in the UK and elsewhere. “
Another worrying variant, known as P1 or B1128, was first detected in January in travelers arriving in Japan from Brazil. It shares some of the same mutations as B1351, and globally has over 20 changes, deletions, mutations, and insertions in its genome. A report by Brazilian researchers said it was “potentially associated with increased transmissibility or the propensity for reinfection of individuals.”
In other words, there are concerns that it may elude the antibody response in people immune to the virus, but there is still a long way to go to establish it. But given that the researchers said that P1 appears to be associated with a rapid increase in cases in places where previous attack rates are considered to be very high, “it is essential to quickly find out if there is an increased rate. re-infection in previously exposed individuals ”.
Then, on January 17, the California Department of Public Health in the United States revealed that a variant known as L452R is increasingly being identified by genomic sequencing in several counties across the state. However, the department said in a statement, “It is too early to know if this variant will spread faster than others.”
“The fact that this variant has been identified in several large epidemics in our county is a wake-up call and needs to be investigated further,” said Dr Sara Cody, County Health Officer. Santa Clara.
Australian health officials fear the variants currently wreaking havoc in the UK, South Africa and Brazil may leak out of hotel quarantine, where returning travelers must self-isolate for 14 days and undergo testing.
Deputy Chief Medical Officer Michael Kidd said on Friday that if a person tested positive for the variants, they would have to undergo an additional 14 days of isolation before being released, compared to 10 days for those diagnosed with less variants. worrying.
There are several theories as to why some variants have managed to take hold while others have died out, Turville said.
“Regarding the variants identified in Brazil and the UK and how they came to be, there is evidence that people infected with the virus for longer accumulate more changes in the virus.”
People who are immunocompromised, such as those with cancer, are infected longer because their bodies cannot fight off the virus as quickly. The theory is that this gives the virus an environment to linger and develop mutations, before it is then passed on to someone else.
But Turville said that in countries where Covid-19 is out of control, the sheer number of people infected makes it more likely that there will be a rare event that will lead to an “explosion of changes in the virus that you wouldn’t see. other” .
“It can boil down to the fact that in the really hard hit areas there is more opportunity for a rare virological event,” he said. Turville and other researchers hope to learn more about these variants through their work in the containment lab at the Kirby Institute, a high-security lab that receives swabs of the virus from international travelers into the Australian hotel quarantine system. .
Turville then uses these swabs to develop the virus. Whenever a person enters the lab, they dress in several layers of clothing covered with full personal protective equipment, including breathing masks, rubber boots, and coveralls on top. Turville passes through a series of negative pressure chambers before entering the containment lab, where he can only work for short periods of time to avoid overheating.
“We get swabs from the quarantine of all the new virus flavors that are seen there, and then we develop them and we have to see how they behave in the lab. This helps us know if a person who had an antibody response after being infected with a different variant in March will show a response similar to one of the more recent variants. “
Turville said the good news was that while some of the newer variants may attenuate an antibody response or a vaccine response, none to date could completely escape the immune response.
“To date, we have yet to see a single mutant virus with a complete immune breakout that would render a vaccine useless,” he said.
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