How do the variants of the new coronavirus arise?

Infectologist: There will be no herd immunity due to variants 2:21

(CNN) – The woman over 30 years of age was not ill for long. After being admitted to the hospital with COVID-19, he needed some oxygen and was given steroids, but recovered enough to go home after nine days.

However, the virus remained in his body for seven months, mutating multiple times as he struggled with his immune system, which was not very good.

This is how the variants of the new coronavirus emerge.

The longer the coronavirus has in a body, the more likely it is for variants

All viruses constantly mutate when they replicate in a host body. The more people that are infected, the more likely the virus is to evolve through a process known as mutation.

“The longer the virus has, and the longer it has to cope with people’s antibody responses, the greater the chance that variants will emerge,” said Penny Moore, a virus expert at the National Institute of Communicable Diseases in South Africa. , in a webinar, organized earlier this month by the International Antiviral Society.

In this case, the patient, over 30 years old, from South Africa, was infected with the human immunodeficiency virus (HIV), which causes AIDS. His HIV was not well controlled and had damaged his immune system, giving the virus the advantage it needed to survive in his body for more than 200 days.

In other cases, people take immunosuppressive drugs because they have undergone organ transplants or to fight autoimmune diseases. Or they may simply have an immune system that is slow to respond to infection.

But all over the world, on any given day, the virus is infecting people and mutating in their bodies. When those mutations give the virus some kind of advantage – the ability to replicate more quickly or hide from the immune system – that version will outperform the rest.

Vaccines, a way to stop the variants

That’s why public health officials around the world are crying out for people to get vaccinated as soon as possible. People who don’t get infected don’t keep an ever-changing virus in their bodies.

“The only way we’re going to be able to get rid of the variants is by reducing the number of infections,” said Moore.

And the evidence indicates that current vaccines used in the United States and many other countries work well to protect people against infection in the first place.

“Current data suggests that the COVID-19 vaccines licensed for use in the United States offer protection against most of the variants that are currently spreading in the country.

‘However, some variants could cause the disease in some people even after being fully vaccinated. These are the so-called vaccine break cases, ”spokeswoman for the Centers for Disease Control and Prevention (CDC), Jade Fulce, told CNN in an email on Friday.

A new variant of coronavirus on the sixth day of treatment for the South African patient

The South African patient had not yet been vaccinated. He became infected in September 2020, months before vaccines were available.

She volunteered for a clinical trial, so the KwaZulu-Natal University team was able to take regular blood samples and virus samples to see what was going on in her body.

She was infected with the world’s first recognized variant of the new coronavirus, one called D614G. By the sixth day of his treatment, the virus in his body had acquired another mutation, one called E484K. It is concerning because it helps the virus evade the human immune response.

Day 190

“On day 190, the D427Y and N501Y mutations appeared,” Tulio de Oliveira and colleagues at the University of KwaZulu-Natal in South Africa wrote in an online prepublication report.

The N501Y mutation makes the virus more contagious.

“All viruses have a receptor that allows them to attach to a cell, and that is the beginning of the infection process,” explained Moore. “And in some cases, how well that virus is able to bind to the host cell receptor really is a game changer for that virus,” he added.

«A virus that has an advantage in terms of binding […] it means that it has a much better chance of infecting cells, “he said.

So viruses carrying that type of mutation would be more successful, and more likely to replicate and spread than viruses without the mutation.

“A lot of what we’re seeing now with variants is that,” Moore said.

Mutations of the beta, gamma and alpha variants of the new coronavirus

Delta variant forces to evaluate measures against covid-19 0:50

There are other more worrisome mutations.

“Another is the ability to become somewhat more invisible to the human immune system. When we talk about immune evasion or antibody escape mutations, that’s what we mean, ”said Moore.

‘The virus has changed its coat by incorporating one of these mutations to allow itself to be somewhat less visible. It is as if it is hiding from the immune system under an umbrella because it has managed to mutate its coat in some way, “he added.

The virus variant B.1.351, first observed in South Africa and now called the beta variant, has the E484K and N501Y mutations. The same occurs with the P.1 variant, seen for the first time in Brazil and also known as gamma. This means that they can replicate more easily and also evade the effects of the human immune response, as well as monoclonal antibody treatments and, to some extent, vaccines.

The immune system’s ability to hide is what really scares us about these variants, “said Moore.

The B.1.1.7 or alpha variant, first seen in the UK, has the N501Y mutation, but not usually the E484K mutation.

Not just a patient – mutations arise in multiple parts of the world

So in just one patient, all of these changes occurred when the virus stayed one step ahead of his immune system.

“Despite being a short clinical disease of moderate severity, the SARS-CoV-2 PCR positivity persisted for up to 216 days. We show that there were significant changes in the virus population during that time, with multiple mutations, ”De Oliveira and colleagues wrote.

This does not mean that a single patient was the source of the beta variant, or the source of any spread of the variant at all. These mutations are emerging in multiple patients in multiple locations around the world, all at the same time.

“It seems to be throwing up very similar mutations in different parts of the world,” Richard Webby, an infectious disease expert at St. Jude Children’s Research Hospital in Memphis, told CNN.

How would you protect vaccines from coronavirus variants?

The normal immune response to coronavirus infection is immediate and overwhelming.

This is where the pressure on this virus comes in. It does not mutate for fun. It changes to get rid of this robust immune response, ”said Moore.

This is even more evident in the case of fully vaccinated people. Many studies have shown that certain vaccines, especially those of mRNA manufactured by Pfizer / BioNTech and Moderna, and to a lesser extent the Johnson & Johnson vaccine, elicit a broad immune response, much broader and stronger than that following natural infection. .

‘They trigger massive amounts of antibodies. And that means that even if there is a hit against that virus that even has its umbrella that protects it, there is still, we think, enough activity from those vaccines to be able to deal with the variant, “said Moore.

“So potency is the center of attention when it comes to vaccines,” he added.

People who have never been vaccinated, or who have only been partially vaccinated, are more likely to become infected, especially with a variant that can already partially elude the immune response. Data from the US CDC shows that 10% or more of Americans who received one dose of the Moderna or Pfizer vaccine did not receive the second dose.

“Please,” CDC director Dr. Rochelle Walensky told NPR on Friday, “put on the second dose.”

CNN’s Lauren Mascarenhas contributed to this story.

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