Thursday, March 23, 2023

How Do Viruses Mutate And Become Resistant To Vaccines

How The Omicron Variant Got So Many Scary Mutations So Quickly

Why does the Covid-19 virus mutate? | Wellcome

The numerous changes in the coronaviruss spike protein could have arisen in an isolated population or an immunocompromised personor animals

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On November 25, South African scientists announced the discovery of a new, heavily mutated variant of the coronavirus, triggering global panic. Countries quickly imposed travel bans and closed their borders, but the variant has already been detected in at least 23 countries, including the U.S.

One reason for the knee-jerk reactions is the new variants high number of mutations: Omicron, as it has been dubbed by the World Health Organization, has more than 30 changes to its spike protein. This protein allows the virus to infect and take over human cells, and is also the target of most vaccines. Spike protein changes in previous variants, such as Delta and Alpha, are thought to have made the virus more infectious or more likely to evade the immune system and vaccines. It is not yet clear whether Omicron is more transmissible, or causes more severe disease than previous variants, or whether it will render the vaccines less effective. But a new pre-print study released by South African scientists on Thursday, which has been not yet been published in a scientific journal, suggests that Omicron is three times more likely to reinfect people.

Mutations develop spontaneously as a virus replicates and spreads, but scientists are now trying to understand how so many mutations arose in Omicron in such a seemingly short space of time.

What Role Does The Environment Play In Mutation

One of the big factors in the mutation rate of viruses is population density, said Brown.

“When you have high density conditions and overcrowding, like you would see in a pig farm, then the mutation occurs much more quickly as it passes from one snout to the next,” he said. The kind of virus likely to thrive is also a function of its environment, he said.

A virus that quickly kills its host as it spreads is more likely to thrive in densely populated areas where it can out-compete other viruses, but would die out when the supply of new hosts is in short supply, he said. Conversely, a virus that incubates in the host for weeks and spreads slowly is more likely to thrive in animals like migratory birds, he said.

Regarding Coronavirus Variants How Concerned Should We Be

Most of the genetic changes we see in this virus are like the scars people accumulate over a lifetime incidental marks of the road, most of which have no great significance or functional role, Ray says. When the evidence is strong enough that a viral genetic change is causing a change in the behavior of the virus, we gain new insight regarding how this virus works. The virus seems to have some limitations in its evolution the advantageous mutations are drawn from a relatively limited menu so there is some hope that we might not see variants that fully escape our vaccines.

Updated versions of the current vaccines are being evaluated, but there is no clinical trial evidence yet that variant-specific vaccines would provide significantly greater protection. Though SARS-CoV-2 is changing gradually, its still much less genetically diverse than influenza.

As far as these variants are concerned, we dont need to overreact, Bollinger says. But, as with any virus, changes are something to be watched, to ensure that testing, treatment and vaccines are still effective. The scientists will continue to examine new versions of this coronaviruss genetic sequencing as it evolves.”

In the meantime, we need to continue all of our efforts to prevent viral transmission and to vaccinate as many people as possible, and as soon as we can.

COVID-19 Vaccine

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How Does A Virus Travel From An Animal Like A Pig To A Human

Viruses spread from one animal to another through close contact, in whatever manner it normally spreads, such as coughing or sneezing in the case of a respiratory virus. Normally, these infections have no impact on the new host since they were not built to infect them. But when one host is infected by two or more strains of a virus like influenza, new combinations can result.

Influenza, for example, has eight distinct segments to its genome, increasing its ability to form new combinations that can include elements of avian flu, swine flu and human flu. It’s these recombined versions of the flu that have the potential to cross over and actually spread through a new host.

Pigs are a particularly good incubator as they have receptors for influenza from all three species, said University of Guelph agriculture professor David Waltner-Toews, author of The Chickens Fight Back: Pandemic Panics and Deadly Diseases that Jump from Animals to People.

“So, if they happen to be around people or birds that have influenza, they will pick them up, and the viruses will mix up inside them.”

And as the flu spreads, its list of available hosts spreads as well. Until five years ago, for example, dogs were not susceptible to influenza, said Dr. Earl Brown, a professor of microbiology at the University of Ottawa Faculty of Medicine. But the flu has since spread to canines through horses.

How Does A Virus Mutate

Vaccines: The Short on Shots

While the idea of a virus mutating might sound scary, its actually quite normal. Viruses mutate constantly. This is especially true of viruses that contain RNA as their genetic material, such as coronaviruses and influenza viruses.

All viruses are made up of a bundle of genetic material thats covered by a protective coating of proteins. Once a virus gets into your body usually through your mouth or nose it latches onto one of your cells. The viruss DNA or RNA then enters your cell, where it can make copies of itself that go off and infect other cells. If the virus can copy itself and hijack enough of your cells without being wiped out by your immune system, thats how you get sick.

Every now and then, an error occurs during the viruss copying process. Thats a mutation.

Most of the time, mutations are so small that they dont significantly affect how the virus works, or they make the virus weaker, Dr. Rhoads says. But occasionally, a mutation helps the virus copy itself or get into our cells more easily.

If these advantageous genetic mistakes are included when the virus replicates, theyre passed on and eventually become part of the viruss normal genome, Dr. Rhoads explains. We can see these mutations accumulate over time, and thats how we get new variants of a virus strain.

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What Causes A Virus To Change To A New Variant

When a virus is widely circulating in a population and causing many infections, the likelihood of the virus mutating increases. The more opportunities a virus has to spread, the more it replicates and the more opportunities it has to undergo changes.

Most viral mutations have little to no impact on the viruss ability to cause infections and disease. But depending on where the changes are located in the viruss genetic material, they may affect a viruss properties, such as transmission or severity .

The Idiot’s Guide To Viral Mutation

We need new coronavirus variants like a duodenal ulcer, but they’re here something any virologist would have said was inevitable. Here’s a lesson on how mutation works. Plus an explanation of what those crazy letters and numbers mean that you see in the news.

As if we don’t have enough problems.

COVID-19 is way more than bad enough, so pretty much the last thing we needed was the emergence of mutated forms of the damn thing. But it was unavoidable. Why? Because of natural selection. This is how viruses thrive by spontaneously “improving” themselves, which can make them more contagious, more virulent , or any of these.

The clever little devils also mutate in response to a drug or vaccine, again ensuring that they thrive. The mechanism is the same, but in this case, selective pressure rather than random errors is the driving force behind mutation. Let’s say that a person infected with Virus A is treated with an antiviral drug that prevents replication of Virus A. The drug works by stopping one of the essential steps required to build new virus particles. Is this the end of Virus A? Hell, no.

When new variants emerge, they need to be identified by a name or number. That’s why we are seeing all those bizarre-looking numbers and letters attached to the virus. But it’s not really complicated. The numbers and letters actually make a lot of sense. Here’s why:

So What?

It Gets Worse

Codon Amino acid

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Beyond Omicron: Whats Next For Covids Viral Evolution

As the world sped towards a pandemic in early 2020, evolutionary biologist Jesse Bloom gazed into the future of SARS-CoV-2. Like many virus specialists at the time, he predicted that the new pathogen would not be eradicated. Rather, it would become endemic the fifth coronavirus to permanently establish itself in humans, alongside four seasonal coronaviruses that cause relatively mild colds and have been circulating in humans for decades or more.

Bloom, who is based at the Fred Hutchinson Cancer Research Center in Seattle, Washington, saw these seasonal coronaviruses as potentially providing a roadmap for how SARS-CoV-2 might evolve and for the future of the pandemic. But little is known about how these other viruses continue to thrive. One of the best-studied examples a seasonal coronavirus called 229E infects people repeatedly throughout their lives. But its not clear whether these reinfections are the result of fading immune responses in their human hosts or whether changes in the virus help it to dodge immunity. To find out, Bloom got hold of decades-old blood samples from people probably exposed to 229E, and tested them for antibodies against different versions of the virus going back to the 1980s.

Researchers are learning as they go, says Andrew Rambaut, an evolutionary biologist at the University of Edinburgh, UK. We havent had much to go on.

Can Vaccination Promote Mutations At All

How Does The Coronavirus Mutate? It’s Just A Series Of Mistakes

Theoretically, however, there is the possibility that vaccinations exert an immunological pressure on the virus, says Georg Behrens. “Then it tries to escape this pressure through such a mutation,” he said.

That is because the virus is currently encountering populations that are only partially vaccinated. As a result, some people have an immune response, while others still offer the possibility of becoming infected. “That’s what the virus loves,” said Behrens. “And this can lead to other mutations. This is how the virus trains itself, basically.”

In summary: In very rare cases, vaccinations can cause mutations to arise and theoretically promote their spread, but it is much more likely that dangerous mutations are created where a virus can spread quickly and unhindered.

This article was translated from German.

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The Coronavirus Pandemic: Key Things To Know

The latest Covid data in the U.S.As the Omicron surge causes case counts to reach record highs and hospitalizations to surpass the height of the Delta wave, heres how to think about the data and what its beginning to show about Omicrons potential toll across the county.

Around the world.In Europe, Germany is bracing for major protests against restrictions after thousands took to the streets in France and Austria, and a tough new vaccine requirement came into force in Italy. In Uganda, schools reopened after the longest pandemic-prompted shutdown in the world.

Staying safe.Worried about spreading Covid? Keep yourself and others safe by following some basic guidance on when to test and how to use at-home virus tests . Here is what to do if you test positive for the coronavirus.

And scientists say that caution in this kind of situation makes sense. As a virus jumps from people to animals and back again, as it has with mink, there are more opportunities for changes in the virus RNA, changes that could lead to resistance.

Researchers at the University of Pittsburgh have discovered a kind of mutation that hadnt been seen in coronaviruses before and raises fresh concerns about the evolution of vaccine resistance.

As much as Dr. Duprex despises the pandemic, he finds it hard not to admire the elegance of these mutations. Its so cool, its brilliant, he said.

How Do Mutations Arise

Viruses smuggle their genetic information into a host cell in order to multiply. With every reproduction, there are small copying errors, and each of these errors also changes the genetic code of the virus. So it is constantly mutating, and that is quite normal.

Sometimes these mutations make the virus more effective, for example, by allowing it to elude immune reactions such as those brought about by vaccinations or prior illness. Sometimes they make the virus less effective, that is, weaken it. And often they have no effect at all.

In the evolution of virus mutations, the following applies: The strongest variant prevails. In the case of the coronavirus, this means that variants that are more infectious, for example, suppress the less dangerous forms of the virus.

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Covid Q& a: Can We Cut Isolation Do Boosters Last And What Hope For 2022

Q: Why don’t we cut isolation to five days, as the US has?

A: American officials last week halved the recommended isolation period for people with asymptomatic coronavirus to five days.

Amid a surge in cases there are more than half a million new cases in America every day at present it is hoped this will ease staff shortages, with officials arguing that a person is most infectious two days before and three days after symptoms develop.

There was no requirement to test negative before ending isolation.

UK officials have resisted following suit, instead requiring people to isolate for seven days, with two negative lateral flow tests on days six and seven, a move virologist Professor Lawrence Young from the University of Warwick calls ‘the right approach’.

He says: ‘There is no evidence supporting not being infectious after five days, particularly in the absence of a negative test. It’s very risky.’

He adds that Covid does not have ‘an off switch’ and that infectiousness gradually reduces over time, from a peak, around the time when symptoms develop, to nothing. Some people might still be infectious after five days.

US officials recommend that a mask be worn when around others for five days following isolation.

Anecdotally, patients have reported night sweats and low appetite with Omicron symptoms that are not officially listed by US officials.

Q: I’ve read that the booster lasts only ten weeks. Should I worry if I had mine longer ago than this?

How Flu Viruses Can Change: Drift And Shift

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Influenza viruses are constantly changing. They can change in two different ways.

Antigenic Drift

One way flu viruses change is called antigenic drift. Drift consists of small changes in the genes of influenza viruses that can lead to changes in the surface proteins of the virus, HA and NA . The HA and NA surface proteins of influenza viruses are antigens, which means they are recognized by the immune system and are capable of triggering an immune response, including production of antibodies that can block infection. The changes associated with antigenic drift happen continually over time as flu viruses replicate . Most flu shots are designed to target the HA surface proteins/antigens of flu viruses. The nasal spray flu vaccine may target both the HA and NA of a flu virus.

The small changes that occur from antigenic drift usually produce viruses that are closely related to one another, which can be illustrated by their location close together on a phylogenetic tree. Flu viruses that are closely related to each other usually have similar antigenic properties. This means that antibodies your immune system creates against one flu virus will likely recognize and respond to antigenically similar flu viruses .

Antigenic Shift

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What Is A Variant Of Concern

Coronavirus variants are classified in different categories by organizations such as the World Health Organization and the Centers for Disease Control and Prevention .

A variant of interest is a coronavirus variant that, compared to earlier forms of the virus, has genetic characteristics that predict greater transmissibility, evasion of immunity or diagnostic testing or more severe disease.

A variant of concern has been observed to be more infectious, more likely to cause breakthrough or re-infections in those who are vaccinated or previously infected. These variants are more likely to cause severe disease, evade diagnostic tests, or resist antiviral treatment. Alpha, beta, gamma, and delta variants of the SARS-CoV-2 coronavirus are classified as variants of concern.

A variant of high consequence is a variant for which current vaccines do not offer protection. As of now, there are no SARS-CoV-2 variants of high consequence.

Fact Check: Did Covid Vaccines Cause The Delta Variant

The delta variant is spreading rapidly even in countries with a high vaccination rate. That gives grounds for wild speculation: Did the vaccines make the delta variant possible in the first place? A DW fact check.

Coronavirus vaccination campaign in the Netherlands

In the UK, the number of coronavirus cases has recently been increasing rapidly. Some 95% of the sequenced cases can be traced back to the delta variant. But two-thirds of the population there have already been vaccinated. For some, that doesn’t make sense: How can the mutation spread so quickly despite high vaccination rates?

Opponents of vaccination use this scenario for their own purposes: The German micro-party “Die Basis” is one of many sources spreading speculations on social media that the delta mutation may have been caused by the coronavirus vaccines, albeit without providing any evidence for this theory.

This fact check explains how mutations come about and why vaccines cannot be held responsible for them.

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