New Covid-19 Strains: What Scientists Know About Coronavirus Variants

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

Here’s 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 the genetic code. Over the course of the pandemic, there have been several variants. The ones that were found to be able to spread more efficiently are more common, while others disappear. “It’s like natural selection, like evolution,” said Bettie Steinberg, a virologist and provost at Northwell Health’s Feinstein Institutes for Medical Research.

Why the concern about these particular variants?

Some doctors are concerned that the new variants of the coronavirus could spur the spread of Covid-19, putting additional pressure on hospitals and nursing homes when cases reach their historic peak.

Preliminary data suggests that the new variants are unlikely to cause more serious illness than the more well-known forms of the coronavirus. But even if their virulence is no 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 behavioral and epidemiological data on patterns of disease transmission with mathematical models to determine whether the UK variant is more transmissible than previously identified variants.

They found the new variant to be more transferable than previous variants.

UK contact tracing data shows that patients infected with the new variant infected more people than those infected with earlier variants. Data also suggested that the viral load, or amount of virus in the body, was higher in people infected with the new variant. The higher the viral load for individuals, the more contagious they are.

Is it possible that the rapid spread of the new varieties is not the result of increased contagiousness, but of poor compliance with social disassociation and other anti-contamination measures?

Scientists don’t think so, at least in the UK. As evidence, Prof. Neil Ferguson, an epidemiologist at Imperial College London and member of a scientific panel advising the UK government on respiratory virus threats, pointed to epidemiological data from November showing cases of the new British variant exploding in the area southeast of London, while coronavirus cases fell in other parts of the country. The whole country was trapped during this period.

The situation may be different in South Africa, where researchers said human behavior may play a key role in the increase in cases. Millions of South Africans have traveled extensively in recent weeks, and tens of thousands have gathered in restaurants and bars and on beaches during the holiday season.

Where did the new variants arise?

Like other viral pathogens, the coronavirus spreads by infecting cells and multiplying within them, making copies of itself that spread throughout the body and are then rejected, potentially infecting other people.

The process of reproduction involves copying the genetic code of the virus, which contains the instructions for building successive generations of virus particles or virions. 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 the recently released ones.

Some viruses have genetic codes from DNA, the same molecule that carries genetic information in human cells. Other viruses, including the coronavirus, are based on a related molecule known as RNA. RNA viruses lack a molecular proofreader, a protein that checks for errors and corrects them so that they “pile up more typos faster,” said Dr. Steinberg.

What about the mutations seen in the new variants?

The new variant that emerged in the UK has about two dozen separate mutations, including some related to the prominent protrusions that cover the outer surface of the coronavirus. It is this so-called spike protein that helps the virus infiltrate cells by binding to and then breaking their outer membranes.

In theory, a mutated form of the spike protein could increase the ability of a virus to attach to cells and thus enable it to infect more efficiently. Previous research has shown that one major mutation in the British variant can make the virus more contagious, said Dr. Ravindra Gupta, a University of Cambridge virologist who led the studies.

The South African variety has more than 20 mutations, including some that affect the spike protein. Some are in key spots where antibodies that prevent the virus from entering cells bind, scientists said, meaning they may be able to help the virus bypass a person’s natural immune response.

The variants in the UK and South Africa share a peak protein mutation that allows the peak to bind more strongly to the cell membranes, research suggests.

Do existing vaccines work against new variants?

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

and BioNTech SE and that of Moderna Inc.

To grant immunity to the new variants, scientists have expressed confidence that they do.

The mutations “raise some questions about the efficacy of vaccines, but it is important to note that the vaccines elicit a broad immune response … targeting different areas of the spike protein,” said Dr. Richard Lessells, specialist. in infectious diseases at the University of KwaZulu. -Natal in Durban, South Africa, and a member of the team that discovered the South African variety.

Pfizer and Moderna conducted lab tests with their vaccines against different versions of the coronavirus and found that the vaccines were effective against everyone, according to the drug makers. The companies said they were running experiments to determine whether antibodies generated by vaccinated people were effective against the variants in the UK and South Africa.

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

How can scientists be sure that these new variants spread more easily?

Scientists said they had studied some of the individual mutations of the new variants, but it would be important to look at what happens when they appear together – as with the new variants. That research includes experiments in cells and in animals to test whether the new variants attach better to and enter cells; whether they replicate more easily; and, most importantly, whether they spread more easily.

Animal studies with an earlier coronavirus variant have convinced some scientists that the specific mutations made it more contagious, said Dr. William Hanage, a biologist at the Harvard TH Chan School of Public Health who specializes in infectious diseases. That version of the virus also had a mutated spike protein.

What can be done to stay safe from the new variants?

Infectious disease experts and public health officials say it is important to continue to adhere to known strategies to prevent contamination, including social distancing, masking, and hand washing, and to avoid exposure to other people indoors, especially where there is ventilation arm. Extra care may be needed at indoor meetings if experiments confirm that the new variants are more contagious.

—Joanna Sugden contributed to this article.

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