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This is everything you need to know



This transmission electron microscope image shows SARS-CoV-2 (also known as 2019-nCoV), which is the virus that causes COVID-19. Isolated from American patients, from the surface of cells cultured in the laboratory.

Source: NIAID-RML

Even if the global Covid-19 virus infections decline globally, leading US health officials have warned that as new, more contagious, and possibly more deadly virus variants become popular in the United States, a wave of infections will come.

The scientists were not surprised by the emergence of the new variants, and reiterated that the currently available vaccines should still be able to combat them-although not as effective as against the original “wild”

; strain. However, senior US health officials and infectious disease experts worry that these highly contagious variants, especially the B.1.1.7 strain that appeared in the UK, may reverse the current downward trend in US infections and delay the country’s growth Recovered from the epidemic.

“I think we should assume that the next wave of case growth, as far as we can reach, will be related to B.1.1.7. This is something I think everyone must be more cautious about,” the White House Covid-19 senior Consultant Andy Slavitt told MSNBC last week. “It’s nice to see the number of cases decrease, but it may be misleading.”

Why does the virus mutate

Experts say that as the coronavirus spreads, it will replicate itself a lot, and each version is a little different from the previous version. The virus that causes Covid-19, SARS-CoV-2, has many opportunities to spread and replicate. As more people become infected, problematic mutations are more likely to appear.

The three main “variables of concern” that marginalized US officials were first identified in the UK, South Africa and Brazil. According to a January study by the US Centers for Disease Control and Prevention, the B.1.1.7 variant that was first discovered in the United Kingdom is rapidly multiplying in the United States and may become the country’s main strain in March.

On February 4, Dr. Adam Lauring, an infectious disease expert at the University of Michigan, Ann Arbor, said that through mutation, the virus is only trying to “enter the next host and make full use of itself.” .Like other coronaviruses, SARS-CoV-2 has a slower mutation rate than other viruses I like influenza because it has a kind of “proofreading” enzyme that can repair certain changes while copying.

In other cases, the “escape mutation” adapts the virus to “selective pressure”, that is, when the virus encounters a population that already has a certain degree of immunity to it, whether it is through previous infection, vaccination or antibody treatment, it limits Its ability to spread, but did not stop it.

Laurin said: “You can think of it as trying a new solution.” “This mutation will either make you a better or worse virus, and then you have a choice. The fittest survive because of the lack of better terms of.”

Dr. Dennis Burton, chairman of the Scripps Research Institute, said that studies have shown that people with weakened immune systems may produce more worrying viral mutations because they take longer to respond and clear the virus. Gives us more time to figure out our mutation. Department of Immunology and Microbiology.

Burton told CNBC in a telephone interview: “If someone is infected with this virus and clears it within a few days, you don’t have much chance to mutate.” “But if someone is like a weakened immune system People are infected with this virus, and they hide the virus for several weeks, then it will have more chances to mutate.

Why some are worse than others

Infectious disease experts say that only a few variants become a public health problem. These variants often become more easily spread, cause more serious disease in infected people, or evade certain protections from vaccines and antibodies.

The director of the Centers for Disease Control and Prevention, Dr. Rochelle Walensky, told JAMA on Wednesday that it is believed that the transmission capacity of the B.1.1.7 variant is about 50% higher, and early data suggests that it may be 50% more lethal.

Walensky’s chief medical adviser to the White House, Dr. Anthony Fauci and Dr. Henry Walke, wrote in JAMA’s view that there is also evidence that people infected with an early virus strain may be reinfected by the B.1.351 variant found in South Africa. CDC’s Covid Event Manager.

According to the CDC, SARS-CoV-2 is a type of coronavirus, a large group of viruses, named “corona spikes on its surface.” Researchers monitor whether these spikes or S proteins are mutated, because they can make it easier for the virus to bind to cells or increase the number of viruses that people shed.

The S protein has a so-called “receptor binding domain,” which acts like a “nail’s hand”. It captures the so-called ACE2 receptor on human cells, said Dr. Daniel Griffin, the head of ProHEALTH infectious diseases, told CNBC.

Griffin said that changes in the S protein may be a problem because those spikes have always been targets for neutralizing anti-Covid-19 antibodies, which are produced through natural infection or vaccination. They may also affect the performance of monoclonal antibody therapy, thereby preventing people from developing serious diseases.

For example, according to CDC data, the B.1.1.7 variant first discovered in the UK has several different mutations. One of the key mutations in N501Y is a change in the spike protein, which scientists believe will help the virus to more easily bind to the cell.

The same key N501Y mutation was generated in the B.1.351 variant identified in South Africa and the P.1 variant identified in Brazil. The two strains also developed another method for mutation of their spike protein, called E484K.

The US Centers for Disease Control and Prevention warned that this mutation has been found in some B.1.1.7 cases and may be resistant to antibody drug therapy. Early studies have shown that it may reduce the effectiveness of certain vaccines.

Griffin said to CNBC when talking about the E484K mutation: “This actually worries me.”

What does this mean for vaccines

Although the vaccine is still proven to be effective against these mutations, there are concerns that the B.1.351 strain may pose some challenges.

The large clinical trials of Johnson and Johnson and Novavax reported in late January that their vaccine was immersed in It was tested when the variant first appeared in South Africa. Novavax says its vaccine Among the 44 Covid-19 cases in South Africa, the vaccine has an effective rate of 49%. Johnson & Johnson stated that its vaccine is 57% effective in preventing symptomatic Covid-19.

Kate O’Brien, director of immunization at the World Health Organization, said on Thursday that these results do not provide sufficient certainty because of the small number of cases in the South African trial department.

O’Brien said at the press conference: “We are still in the early stages of interpreting the evidence, and, most importantly, to get more information about the actual occurrence of the disease.” “In general, we see these vaccines. In the absence of highly popular variants, it can still maintain low disease resistance.”

Pfizer and Moderna

The clinical trials of Pfizer-BioNTech and Moderna were conducted before the variants appeared, so scientists have been conducting laboratory tests to determine the response of blood samples from people who have been vaccinated to laboratory-built virus variants with key mutations how is it.

These studies look at whether the serum in the blood neutralizes the virus and prevents its replication. These studies show that performance is reduced when tested against the B.1.351 variant. Walensky, Fauci and Walke wrote in their views: “Due to this variation, people who currently recommend vaccines may not be able to effectively prevent infection.”

However, your body’s ability to fight the virus may not only depend on neutralizing antibodies, including T cells and B cells, which can help fight the virus, but early laboratory evaluations did not evaluate this, Lauring told JAMA.

The good news is that Pfizer and Moderna vaccines also showed such high efficacy in early trials-about 95%. Experts say that therefore having a cushion can reduce its performance, while still being considered effective by doctors. It has also been shown that these shootings can prevent serious forms of disease, which can lead to hospitalization or death.

Both Pfizer and Modena have stated that they are boosting the vaccine to better resist the B.1.351 strain.

Looking for mutations

The B.1.1.7 variant was first discovered in the United Kingdom in December, but it is believed to have appeared sometime in September. Many experts believe that the UK has the ability to perform large-scale genome sequencing to find variants.

According to the CDC, genome sequencing is a laboratory technology that can break down the genetic code of a virus, so that researchers can monitor changes in the virus over time and understand how these changes may affect the virus.

According to the latest CDC data, in the United States, there are now 1,661 Covid-19 cases recorded as the B.1.1.7 variant, 22 cases with the B.1.351 variant, and 5 cases with the P.1 variant. Officials admit that the United States is sorting a small number of cases, and the spread of these variants may be even greater. However, the federal government recently tried to increase the number of samples tested each week to detect these and other mutations that may develop in the country.

The Centers for Disease Control and Prevention (CDC) has partnered with public health and commercial laboratories to rapidly expand the country’s genome sequencing. Valensky told the Journal of the American Medical Association on Wednesday that in January, the United States only sequenced 250 samples a week, and has since “grown to thousands.” She added: “We are not where we need it.”

Dr. Ilhem Messaoudi, director of the Virus Research Center at the University of California, Irvine, said that the process can be time-consuming and labor-intensive, but if the laboratory does not test all positive Covid- she said there are 19 test results that can find new mutations.

Messaoudi said in a telephone interview with CNBC: “Now we are trying to catch up.” “We are like,’Let’s go back and see if there is this.'”

Masks, stay away from society

The rapidly spreading variant once again demonstrates the importance of curbing the spread of the coronavirus through public health measures such as wearing masks, social distancing and hand hygiene, to prevent further mutations and make time for countries to deploy life-saving vaccines.

However, the coronavirus variant is not only a problem for the United States. The head of the CDC warned on Wednesday that if the virus spreads in other parts of the world that have not been vaccinated, it could cause mutations that could threaten the widely deployed vaccines in other countries.

Burton told CNBC that in the end, the entire world will need to increase immunity to the virus, otherwise variants will continue to be a problem.

Burton said: “Sooner or later variants will be everywhere if they have great advantages.” “This is a global problem, not just any one country’s problem.”


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