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The contagions derived from the outbreak of peninsular students who went to Mallorca on their end-of-year trip show us that we are not doing well.
As an inevitable consequence of trying to combine health and economy, even knowing that with infection rates higher than 5 infected per 100,000 inhabitants the risk of variants with bad consequences appearing is very high, we have made the mistake of relaxing anticovid measures when we reach rates of contagion of covid-19 of less than 100 infected per 100,000 inhabitants.
The objective should have been and continues to be to reduce the probability that new variants of SARS-CoV-2, the virus that causes covid-19, will appear, because the appearance of new mutations (and the variants that they carry) is the key to the spectacular coronavirus success. Mutations occur due to random errors as the virus replicates its genome within host cells.
All viruses, including SARS-CoV-2, mutate over time. SARS-CoV-2 mutates regularly, acquiring a new mutation in its genome approximately every two weeks. Most of the changes have little or no impact on the properties of the virus. However, some changes can affect certain properties, such as the ease with which it spreads, the severity of the associated disease, or resistance to vaccines, drugs, or other social and public health measures.
For thousands of years the coronavirus has reproduced in animal species such as pangolins and bats. We did not even know of its existence. The virus mutated and mutated without major consequences. And it is that chance makes the vast majority of new mutations harmful to the virus itself. They work worse than the original ones from which they are derived and the ‘new’ virus is less infectious. In that case, after a short time, the inefficient mutations die out. It is natural selection.
Population genetics shows that thousands of these SARS-CoV-2 mutations have appeared in just over a year. The good news is that almost all of them will have gone extinct without ever being detected by science, although thousands of new mutants are collected in the coronavirus sequencing databases.
The concern began as 2020 dawned: a new SARS-CoV-2 mutation allowed it to start infecting humans. The first strain that began to massively infect humans was that of Wuhan, known as the WIV04 / 2019 variant or “zero sequence”. After unleashing a devastating first wave worldwide, various epidemiological and public health measures managed to reduce its incidence.
But the coronavirus evolved extremely fast through new mutations that turned out to be much more efficient in its transmission, managing to unleash new waves. The mutants of the coronavirus, such as those that originated the already famous British, Brazilian, South African and Indian strains (double mutant), began to monopolize the media headlines and, unfortunately, with little rigor and apocalyptic headlines.
The World Health Organization (WHO) distinguishes three types of variants. The so-called variants of interest (VOIs), which usually have mutations that cause changes in the receptor-binding site of the virus in human cells, affect the efficiency of transmission, making them more infective than the original strains from which they are derived. Often the antibodies neutralize them worse, the disease they cause is more serious, and it responds worse to treatments.
To some extent the efficacy of vaccines is reduced. An example of this variant is the Brazilian 20J strain detected in Manaus, or the 20C strain that appeared in New York in November 2020 and was responsible for the high incidence of covid-19 in this city.
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World Health Organization
The so-called variants of concern (VOC) are worse, because as they present a significant greater reduction in the effectiveness with which the antibodies neutralize them, they have a much greater infectivity, they produce more severe cases of the disease, they reduce the effectiveness of the treatments, reduce the effectiveness of vaccines and lead to higher rates of hospitalizations and deaths. Some of these VOCs were the 20l / 501Y.V1, originated in Great Britain, the 20l / 501Y.V3 that appeared in Japan and Brazil, the South African 0H / 501.V2, and the Californian 20C / S: 452R.
The most fearsome effect that new mutations can cause is to lead to high-consequence variants (HCV). None of these variants have yet occurred, although the US Centers for Disease Control and Prevention warns that they could arise at any time. The consequences would be disastrous, because, in addition to being more resistant to hospital treatments, they could be more infectious and cause higher mortality, they would affect a huge number of vaccinated people and people who suffered from the disease, who could become infected again.
The good news is that the immune response is dynamic and adapts to changes in the virus. The key to the problem is that, as mutations occur randomly, the greater the number of infected (remember that a single COVID-19 infected produces billions of viruses), the more likely we are that mutants capable of producing large variants will appear. consequences (VOHC).
Therefore, our goal should be to prevent variants of all types in general and VOHC in particular from appearing. The increase in infections, although they affect a younger and more resistant population, and many are asymptomatic, is a demonstration that we are not doing it well, because, as in Russian roulette, chance plays against us.
This article was originally published on The Conversation. Read the original.
Manuel Peinado Lorca is responsible for the Federal Biodiversity Group of the PSOE
José Miguel Sanz Anquela does not receive a salary, nor does he carry out consulting work, nor does he own shares, nor does he receive financing from any company or organization that may benefit from this article, and he has declared that he lacks relevant links beyond the academic position cited.