Wednesday, April 14, 2021

The United States has a Covid “scariant” problem. Here’s how to fix it

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This increase in sequencing is helping scientists map the mutational landscape of coronaviruses circulating in the country in more detail. It is therefore not surprising that they are starting to create more surprises. But as the pace of genomic data production has accelerated, there has not yet been a similar and concerted progress in what is called “characterization of variants.”

Sequencing can help you identify mutations that strength be problematic. But it can’t tell you if these mutations cause this version of the virus to behave differently from others. For this you need to conduct studies with antibodies, living human cells, and animal models. Each type of experiment or analysis requires a unique set of skills, and there are many different methods of measuring the same things. You also need immunologists, structural biologists, virologists, and a whole bunch of other scientists. And, ideally, you’d want them all to adhere to the same scientific standards so that you can compare one variant to the next and determine if a new strain is of public health concern or just interesting.

In the United States, the CDC is the primary body with the authority to designate all emerging strains as “variants of interest” or “variants of concern”. Crossing this threshold requires strong evidence that a particular constellation of mutations confers the ability to do one of four things: spread faster and easier, inflict more severe disease, weaken the effectiveness of Covid treatments -19 or escape the antibodies produced either by vaccination. or during a previous infection with an older version of the virus.

So far the agency has only enhanced three new versions from SARS-CoV-2 to the category of greatest concern: B.1.1.7, which was first detected in the UK, B.1.351 in South Africa and P.1 in Brazil. (Although there is an ongoing fight for which code name system to use, most scientists have agreed to avoid the “insert-name-of-place-here” nomenclature because of its imprecision and stigmatizing effect. For simplicity’s sake, we will refer to B.1.1.7, B.1.351 and P.1 from now on as the big three.)

But the agency is currently tracking other variants of interest – including B.1.256 outside New York and B.1427 / 429 in California – and is monitoring ongoing studies to assess the ability of these strains to evade immune responses. and erode the protections offered by existing vaccines. As new data becomes available, the agency may add particularly disturbing variations at this higher level. “The threshold for designating a variant of interest should be relatively low in order to monitor potentially important variants,” a CDC spokesperson told WIRED via email. “However, the threshold for designating a variant of concern must be high in order to focus resources on variants with the most significant public health implications.”

The spokesperson did not provide details of what the agency considers “strong evidence,” but said the CDC has been involved with international partners, including the World Health Organization, in discussion of the criteria for designation of variants.

In other words, it’s not just about finding new variants, it’s about characterizing their biological behavior – what does it mean for someone to be infected with one by compared to the other? “Getting footage is just the beginning of the story,” Topol says. “There is a lot more science that needs to happen to find out if a mutation is significant. And right now, many labs that publish on this topic are only looking at part of the story, because it’s the fastest thing to do. But what is fast can also be misleading. “

For example, a number studies recent weeks have shown that antibodies formed to attack older versions of the virus have a much harder time recognizing the B.1.351 and P.1 variants. This sounded the alarm on the effectiveness of vaccines. But just because the antibodies don’t also fight these new mutants in a test tube doesn’t mean your immune system will have the same problems in a final real boss fight. The immune system is more than antibodies, and far fewer labs have the expertise to perform tests with living T cells. the other major player in the development of Covid-19 immunity. These cells, which eliminate the virus by eliminating herds of infected cells, are difficult to grow outside the human body. So it took a bit longer to figure out how they react to the variants. But new data suggests they are responding very well.

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