A nurse prepares to vaccinate a health worker at the Berks Community Health Center in Reading, Pa. January 6 Credit – MediaNews Group via Getty Images – Copyright – 2021 Image MediaNews Group
As we begin the second year of the new coronavirus SARS-CoV-2, the virus is celebrating its invasion of the world population with even more mutated forms that help it spread more easily from person to person.
One, which was first detected in the UK in December, has already raised alarm over whether the COVID-19 virus is now escaping the protection that vaccines that have just been rolled out may offer. The variant was also found in the USA. Officials in the UK have tightened lockouts in England, Scotland and Wales, and over the holiday more than 40 countries have banned travelers from the region in an effort to prevent the new tensions from spreading to other parts. of the world. Health officials are also concerned about another species that occurs in South Africa and that may be more resistant to vaccine protection. This variant contains single mutations in key regions targeted by antibodies generated by the vaccine.
Exactly how the new strains affect people who are infected – such as whether they develop worse symptoms – and whether it can cause more hospitalizations and deaths is not yet clear. But scientists are making efforts to genetically sequence more samples from infected patients to learn how wide they are. So far, there are enough tips to worry public health experts.
The fact that SARS-CoV-2 is turning into more dangerous breeds is no surprise. Viruses mutate. They have to make a critical mistake in their makeup. Unlike other pathogens such as bacteria, fungi and parasites, viruses have no machinery needed to make more copies of themselves, so they cannot reproduce on their own. They rely entirely on the hijacking of the reproductive instruments of the cells they infect to generate their offspring.
Being such freelancers means that they can not be picky about their hosts, and that they have to make do with the cellular equipment they can find. This usually results in a flurry of errors when they sneak in to copy their genetic code; consequently, viruses are among the most sloppy genomes among microbes. Most of these mistakes are meaningless – false beginning and dead ends – which have no effect on man. But as more mistakes are made, the chance that one can make the virus better by slipping from one person to another, or pumping out more copies of oneself, increases dramatically.
Fortunately, coronaviruses in particular generate these genetic defects more slowly than their cousins such as flu and HIV – scientists who sequenced thousands of SARS-CoV-2 samples from COVID-19 patients found that the virus makes about two errors a month. According to GISAID, a public genetic database of the virus, it has so far led to about 12,000 known mutations in SARS-CoV-2. And some inadvertently pose a greater threat to public health.
Just a few months after SARS-CoV-2 was identified in China last year, a new variant called D614G replaced the original strain. This new version became the largest one to infect much of Europe, North America, and South America. Virus experts are still unsure about how important D614G, named after the site of the mutation on the viral genome, was in human diseases. But so far, blood samples from people infected with the strain show that the virus can still be neutralized by the immune system. This means that the current vaccines that are being rolled out worldwide can also protect against this stress, as the shots are designed to generate similar immune responses in the body. “If the public is concerned about whether vaccine immunity can cover this variant, the answer will be yes,” said Ralph Baric, professor of epidemiology, microbiology and immunology at the University of North Carolina Chapel Hill, who studied coronavirus for several decades.
The so-called N501Y variant (some health officials also call it B.1.1.7.), Which was recently detected in the UK and US, may be a different story. Based on laboratory and animal studies, researchers believe that this strain can spread more easily between humans. This is not a surprise, says Baric, as most of the world’s population has not been exposed to SARS-CoV-2 to date. This means that the strains that are better at jumping from one person to another have the advantage of spreading their genetic code. But as more people are vaccinated and protected from the virus, that may change. “The selection conditions for virus development currently favor rapid transmission,” he says. ‘But as more and more of the human population becomes immune, the selection pressure changes. And we do not know in which direction the virus is going. ”
In the worst case, the changes could lead to the virus becoming resistant to immune cells currently available through vaccines. The current mutants are the virus’ first attempt to maximize the cooperation of the human population as viral copiers. But they can also serve as a backbone on which SARS-CoV-2 builds a more sustained and stable takeover. Like a prisoner planning a prison sentence, the virus is disappearing its time and cutting down the defenses that have built up the human immune system. For example, the virus can mutate in a way that changes the composition of its vein proteins – the part of the virus where the antibodies of the immune system try to keep neutralizing the virus. And that one mutation may not be enough to protect the virus against those antibodies. But two or three may.
The biggest concern at the moment, Baric says, is that there are already two or three variants of SARS-CoV-2 that have mutations at such sites, “where additional mutations could make a more significant change in terms of transmissibility or virulence. “
The best way to monitor evolution is by arranging the virus as often as possible in as many people as possible who are infected. Only by detecting how SARS-CoV-2 changes can scientists hope to stay ahead of the most dangerous and potentially deadly mutations. In November, the US Centers for Disease Control (CDC) launched a sequencing program that would require each state to send ten samples of infected people every two weeks to make changes in SARS-CoV-2s more consistent. to track. genome. But it is a voluntary program. “It’s still not a national effort, it’s voluntary, and there’s no dedicated funding for it,” Baric said. “Come on, we’re in the 21st century – let’s enter the 21st century.”
Without substantial federal funding specifically dedicated to the succession of SARS-CoV-2 genomes, most work in the United States is currently done by scientists at academic centers such as the Broad Institute of MIT and Harvard and the University of Washington. Since early last year, the CDC has been working to better characterize SARS-CoV-2 viruses from patient samples in partnership with some of these academic laboratories, as well as state and local health departments and commercial diagnostic enterprises, in the SARS-CoV-2 Order for the consortium of public health, epidemiology and surveillance (Public Health Emergency Response, Epidemiology and Surveillance (SPHERES)): “If we follow one of the 200 cases, we miss a lot of information,” says Baric. ‘If we follow about 20% of the order, we can start to see something, and we’re in the ball game to find new variants. We can probably do better here in the US ”
Other countries are also working on this effort. The UK has long been a leader in genetic sequencing, and probably because of their efforts, they were able to identify the new variant relatively quickly after it emerged. Worldwide, scientists have also placed genetic sequences of SARS-CoV-2 in the public GISAID database.
Dr Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, and chief medical adviser to President-elect Joe Biden, says his teams are studying the new variant and studying it to better understand what effect it can have on the disease. , how it is close to the serious cause of disease and, more importantly, as more people are vaccinated, or the new variant can escape the protection of the vaccines we know today.
The good news is that if the mutant strains are resistant to current vaccines, the mRNA technology behind Pfizer-BioNTech and Moderna should enable companies to develop new shots without doing the same lengthy development and testing as the original required. “The mRNA platform is extremely flexible to turn around,” says Fauci. If a new vaccine is needed, it will be treated by the Food and Drug Administration as a strain change in the virus target, similar to the way flu shots change every year. “You can get it out pretty quickly,” says Fauci, after showing in several dozen people in tests that the new vaccine provides satisfactory amounts of antibodies and protection against the mutant virus.
Detecting every change the virus makes is crucial to buying the time to shift vaccine goals before SARS-CoV-2 leaps too far ahead of scientists. ‘We take [these variants] seriously and will follow them closely to make sure we do not miss anything, ”says Fauci.