New Covid-19 strains: what scientists know about coronavirus variants

Meanwhile, in South Africa, doctors and researchers battling a second wave of Covid-19 cases are studying another new variant and what role it plays in the growing march of cases there. The variant, known as B.1.351, has been identified in samples dating back to October. Not detected in the US

This is what we know so far about the new variants and the genetic mutations that characterize them, as well as their potential impact on public health.

What is a viral variant?

Viral variants are new versions of a virus that arise as a result of small changes in its genetic code. Throughout the pandemic, there have been several variants. Those that have proven to be able to spread more efficiently have become more frequent, while others are sinking. “It’s just like natural selection, like evolution,” said Bettie Steinberg, a virologist and provost at Northwell Health’s Feinstein Medical Research Institutes.

Why worry about these particular variants?

Some doctors worry that new variants of the coronavirus may overload the spread of Covid-19, putting more stress on hospitals and nursing homes as cases approach their all-time highs.

Preliminary data suggest that new variants are no more likely to cause serious disease than the more familiar forms of coronavirus. But even if its virulence is not greater, the seemingly increased transmissibility of the variants could mean more misery and death by increasing the number of Covid-19 cases.

Researchers at the London School of Hygiene and Tropical Medicine combined epidemiological and behavioral data on disease transmission patterns with mathematical models to determine whether the UK variant is more transmissible than the previously identified variants.

They found that the new variant was more transmissible than the previous variants.

UK contact monitoring data show that patients infected with the new variant infected more people than those infected with previous variants. The data also suggested that the viral load or amount of virus in the body was higher among people infected with the new variant. The greater the viral load on individuals, the more infectious they tend to be.

Is it possible that the rapid spread of new variants is not the result of an increase in infectivity, but rather a lack of adherence to social distancing and other measures aimed at curbing the contagion?

Scientists don’t think so, at least in the UK As evidence, Professor Neil Ferguson, an epidemiologist at Imperial College London and a member of a scientific group advising the British government on respiratory virus threats, noted epidemiological data from the UK. November showing that cases of the new UK variant were exploding in south-east London as coronavirus cases fell in other parts of the country. Throughout this period, the whole country was closed.

The situation may be different in South Africa, where researchers said human behavior could be playing a key role in increasing cases. Millions of South Africans have traveled extensively over the past few weeks and tens of thousands had gathered at restaurants and bars and on beaches during the holiday season.

What led to the new variants?

Like other viral pathogens, coronavirus spreads by infecting cells and reproducing within them, creating copies of itself that spread throughout the body and then detach, potentially infecting other people.

The process of reproduction involves copying the genetic code of the virus, which contains instructions for building successive generations of virus or virion particles. But the code is not always faithfully reproduced; sometimes the copying process produces errors that researchers have compared to typographical errors. This is what gives rise to new viral variants such as those that have emerged recently.

Some viruses have genetic codes of DNA, the same molecule that carries the genetic information of human cells. Other viruses, including the coronavirus, are based on a related molecule known as RNA. RNA viruses do not have a molecular corrector, a protein that checks for errors and corrects them, so they “accumulate more typos more quickly,” Dr. Steinberg said.

What about the mutations seen in the new variants?

The new variant that appeared in the United Kingdom has approximately two dozen separate mutations, including some related to the prominent outcrops that study the outer surface of the coronavirus. It is the so-called ear protein that helps the virus to infiltrate the cells by binding to the outer membranes and then violating them.

In theory, a mutated form of the spike protein could increase a virus’s ability to bind to cells and thus allow it to become infected with increased efficiency. Previous research has shown that a mutation in the UK variant can make the virus more infectious, said Dr Ravindra Gupta, a Cambridge University virologist who conducted the studies.

The South African variant has more than 20 mutations, including several that affect the ear protein. Some are found at key points where antibodies bind that prevent the virus from entering cells, scientists say, which means they could help the virus elude a person’s natural immune response.

Variants in the UK and South Africa share a spike-protein mutation that allows the spike to bind more closely to cell membranes, the research suggests.

Do existing vaccines work against new variants?

Although there is still no final word on whether the existing vaccine was made by Pfizer Inc.

and BioNTech SE and Moderna Inc.

to confer immunity to new variants, scientists have expressed confidence.

The mutations “raise some questions about the effectiveness of vaccines, but it’s important to keep in mind that vaccines elicit a broad immune response … that targets several areas of the ear protein,” Dr. -He was born in Durban, South Africa, and a member of the team that discovered the South African variant.

Pfizer and Moderna have conducted laboratory tests of their vaccines against various versions of the coronavirus and have found that the vaccines are effective against all, according to drug manufacturers. The companies said they were conducting experiments to determine if the antibodies generated by the vaccinated people were effective against variants in the UK and South Africa.

The Centers for Disease Control and Prevention continues to urge people who are eligible for vaccination to receive the vaccines. “Based on studies with other viruses that contain similar mutations, CDC believes there will be little or no impact on immunity to natural infection or vaccination,” the agency said in a statement Tuesday.

How will scientists know for sure if these new variants spread more easily?

The scientists said they had studied some of the individual mutations in the new variants, but that it would be important to look at what happens when they appear together, as they do in the new variants. This research involves experiments in cells and animals to see if new variants adhere to and enter cells more efficiently; if they replicate more easily; and, most importantly, if they propagate more easily.

Studies in animals with an earlier variant of coronavirus convinced some scientists that their particular mutations made them more infectious, said Dr. William Hanage, a biologist at Harvard’s TH Chan School of Public Health, who specializes in infectious diseases. This version of the virus also had a mutated spike protein.

What can be done to protect yourself from new variants?

Infectious disease experts and public health officials say it is important to continue to adhere to family strategies to prevent infection, including social distancing, masking, and hand washing, as well as avoiding exposure to other people in indoor environments, especially in ventilation areas. he is poor. Additional attention may be needed in indoor meetings if experiments confirm that the new variants are more infectious.

—Joanna Sugden contributed to this article.

Write to Daniela Hernandez at [email protected] and Sarah Toy at [email protected]