Face mask and social distancing, two powerful tools that help prevent SARS-CoV-2 mutations, new study finds

The advance of COVID-19 infections around the world is creating fertile ground for the emergence of new mutations in the SARS-CoV-2 virus, scientists have warned. They also agreed that mass vaccination is the best defense for containing infections regardless of the strain. Corn a new study published today in Scientific report Based on mathematical projections, he warned against the need to supplement vaccines with other preventive actions, because, as there is a relaxation of “non-pharmaceutical” measures, such as wearing a mask and social distancing, at a time when a large number of people have already been vaccinated “the probability of the appearance of a resistant strain has considerably increases”, insured.

“As expected, we have found that a rapid vaccination rate decreases the likelihood of emergence of a resistant strain. Contrary to intuition, when there was a relaxation of non-pharmaceutical interventions at a time when most of the population had already been vaccinated, the likelihood of a resistant strain was greatly increased, ”the researchers said. authors of the study signed, among others, by Simón A. Rella, from the Austrian Institute of Science and Technology, with Emmanouil T. Dermitzakis, from the Department of Genetic and Developmental Medicine, Faculty of Medicine, University of Geneva, Switzerland .

“Our results suggest that policymakers and individuals should consider maintaining non-pharmaceutical interventions and transmission reduction behaviors throughout the vaccination period. when there was a relaxation of non-pharmaceutical interventions at a time when the majority of individuals in the population had already been vaccinated, the probability of a resistant strain was greatly increased, ”insisted the authors of the screening study.

The The Centers for Disease Control and Prevention (CDC) this week revised their guidelines for wearing face masks indoors to help slow the spread of COVID-19.. The change is implemented two months after the agency relaxed its recommendation to wear masks, saying that fully vaccinated people no longer need to wear them in closed public spaces. Since then, the agency has also noted that vaccinated adults and adolescents no longer need to wear masks in summer camps and schools.

The CDC’s new “masking” advice was based in part on data showing that the virus can thrive in the airways of people who have been vaccinated. The recommendation was largely based on a disturbing finding, according to Dr. Rochelle Walensky, director of the CDC. “New research has shown that vaccinated people infected with the Delta variant carry huge amounts of the virus in their nose and throat,” Walensky said.

An internal document from that organization that was released today indicates that the Delta variant is more transmissible than the viruses that cause MERS, SARS, Ebola, colds, seasonal flu and smallpox.

The World Health Organization (WHO) calls the more serious “disturbing variants” and has decided to name them with Greek letters. So, those who receive the aforementioned categorization are Alpha, Beta, Gamma, and Delta. All four appeared in the second half of 2020, although it took some time for the more transmissible variants to spread more widely. The next category of “variants of interest”, suspected of being more transmissible or resistant to vaccines, includes Eta, Iota, Kappa and Lambda.

Scientists have previously warned that further evolution of the virus is inevitable due to how the genetic code can be altered by errors in the copying mechanism during replication. Mutations can be neutral, but occasionally the “fitness” of the virus increases, allowing it to infect human cells more easily, which would be, for example, the case of Delta, the variant which dominates the world and which, according to experts, it is inevitable that it begins to circulate in Argentina, 46 cases had been detected until yesterday. This number has been changed following the traveler from Lima, Peru, who infected 13 family members with coronavirus in Cordoba province, 12 of whom were detected as the Delta variant, health authorities have already isolated around 160 people considering them close contacts of confirmed cases.

Based on the tremendous progress of the disease around the world, Scientists warn dangerous new phase of pandemic has entered as third wave of coronavirus creates fertile ground for new variants more infectious and potentially resistant to vaccines.

“We have been surprised more than once by the evolution of the variants, although perhaps we should not have been surprised because the virus has recently moved to humans and is still adapting to its new ones. hosts, “said Nick Loman, professor of genomics. the University of Birmingham in the United Kingdom. “We have already been honored by this virus and no one can predict for sure what will happen in the future.”

Infections worldwide have reached an average of 540,000 per day and an average of nearly 70,000 deaths per week, the WHO said this week, driven by the more transmissible Delta variant.

In addition to spreading in countries with low inoculation rates, a study by the Austrian Institute of Science and Technology and the Department of Genetic Medicine and Development at the Faculty of Medicine at the University of Geneva, published this Friday in Scientific reports, found that the danger of establishing vaccine-resistant strains was greatest when more than 60 percent of the population was vaccinated and that other measures, especially the use of masks and restriction of social contact, were been lifted.

“Establishing a resistant strain at that time may lead to series of evolutions of resistant strains, with the development of vaccines catching up with the evolving arms race against new strains,” the study said.

“We are trying to understand why Delta is more communicable,” said Maria Van Kerkhove, WHO COVID-19 technical manager. “Some of the mutations make it easier for the virus to adhere to the cell and therefore infect it.”

Delta is about twice as transmissible as the Alpha variant first registered in England, which was itself 40% more infectious than previous forms of the virus first detected in China, according to data from international studies.

The R0 replication number, which measures transmissibility, is estimated to be around 3 for the parent virus in Wuhan and around 6 for Delta, Loman said at the University of Birmingham. This means that an average person infected with Delta in a population unprotected by vaccination, previous infection and social distancing measures would pass it on to six other people.

Most of the variants of interest or concern have accumulated about 20 individual mutations in the 30,000 biochemical letters that make up the genetic code. Molecular research conducted by virologists such as Ravi Gupta, professor of microbiology at the University of Cambridge, aims to better understand how they affect the behavior of SARS-CoV-2.

Gupta said the changes in the spike protein, which allow the virus to enter human cells more efficiently, appear to be more prominent, although more research is needed. “We know some of the mutations involved, but we don’t know the full story,” he added.

Among the existing variants, Beta, which appeared in South Africa, seems to be the most capable of re-infecting the vaccinated. Beta fears have led the UK to place France in a special ‘amber plus’ travel category this month. French experts say the UK miscalculated as Delta is quickly replacing Beta as France’s dominant variant. “The Beta variant was replaced by the Delta variant in all the places where it circulated together. It’s less ‘appropriate’, “says Sylvie Van der Werf, molecular geneticist at the Institut Pasteur in Paris.

The precise process by which the virus acquires a series of mutations with enough impact to qualify as a new variant remains a mystery, although it can sometimes occur in an individual with a prolonged infection. Gupta and his colleagues studied a Cambridge patient with a weakened immune system in whom the virus replicated for more than three months before dying. A series of mutations similar to those seen in the Alpha variant developed, although this one-man variant did not infect anyone else.

“Some data from Brazil suggests that Gamma may have evolved there through intermediate forms in a phased fashion during the first wave of the pandemic rather than in an individual, although there was not enough monitoring. genomics at the time to capture the process. “said Oliver Pybus, professor of evolution and infectious diseases at the University of Oxford.

It is not yet clear to what extent SARS-CoV-2 can evolve as it adapts to a host population. who is increasingly immune to infection and vaccination.

Most viruses that persist in human populations eventually became less virulent over a period of decades or centuries; It is believed that some coronaviruses that now cause mild cold-like symptoms initially caused more serious illness, but scientists warn that this is not an inevitable process.

“The more the virus circulates, the more it will change,” warned Kerkhove of the WHO. “The delta won’t be the last variant of concern you hear us talk about,” he said.

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