Covid-19, there are three criteria for distinguishing the variants of the coronavirus

Covid-19, there are three criteria for distinguishing the variants of the coronavirus


From variants that draw attention to those that cause concern to those with important consequences: the new classification of the coronavirus variants of the US and WHO CDCs

(illustration: Getty Images) They have now been discovered already a few thousand variants of the Sars-Cov-2 coronavirus - the latest data from February 2021 indicated about 4 thousand - and not all of them are relevant because they are more contagious or dangerous. But then how to recognize the variants to which attention should be paid and those that, on the other hand, will probably not have a particular role in the epidemic? The respondents today are the US Cdc Centers (Centers for Disease Prevention and Control) which, together with the World Health Organization (WHO), have drawn up a new classification to distinguish the variants of the coronavirus.

Many variants, some relevant

In general, a variant has one or more mutations that differentiate it from the other forms in circulation. The virus changes continuously and for this reason it is normal for numerous new mutations to appear all over the world, some of which, especially when recurrent, are more easily identified. Monitoring and studying how and which variants may have an impact on the transmissibility or severity of the Covid-19 infection is essential to understand how the epidemic and pandemic evolves. To facilitate this task, the WHO and the CDC provide a scheme for framing the characteristics of a mutation. The scheme provides for the division of the variants of the coronavirus into 3 categories that meet different criteria. Here they are.

Variants of interest

Variants of interest are those that have caused a good number of Covid-19 outbreaks in the United States or other countries or that appear to underlie a increase in cases. They also have a mutation that suggests a possible increased contagiousness or that could cause the virus to escape recognition by the immune system, possibly making vaccines less effective. However, there is still talk of suspicions to be ascertained and their prevalence in the US and other states must still be limited: for this reason they arouse interest and not yet a real alarm. Currently, the Cdc centers in the US are monitoring 3 of these variants of the coronavirus which are B.1.526, a new form that emerged in New York and which has been reported since the end of February 2021, B.1.525, discovered in the United Kingdom but probably emerged earlier in Nigeria as well, and a Brazilian variant (not the most well-known strain).

The variants of concern

Moving up the ladder there are variants that cause concern, those forms for which researches have confirmed the suspicions of greater transmissibility or lethality. These may be less recognized by diagnostic tests and underlie less efficacy of some therapies and vaccines. Furthermore, people who have already had Covid-19 could also face a second infection precisely because these variants have potentially significant differences. Currently the Cdc centers are monitoring 5, which are: the so-called English variant, prevalent in Italy (and in other countries), the Brazilian variant, the South African variant and the two Californian variants.

The variants with significant consequences

The third criterion, the most stringent one, concerns variants with significant consequences. Fortunately, no variant currently falls into this category. These mutated forms cause more serious illnesses and more hospitalizations. Furthermore, there must be evidence that these variants are able to evade clinical countermeasures such as diagnostic tests, vaccines and therapies such as antivirals and monoclonal antibodies.

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