Variant Mu: know all about the new strain monitored by WHO – Health

WHO monitors cases of the Mu variant, which may fall into the 'concern variant' category (photo: Pixabay/Reproduction )
WHO monitors cases of the Mu variant, which can fall into the ‘concern variant’ category (photo: Pixabay/Reproduction)

In late August, a new variant of the coronavirus, identified in January in Colombia, joined the list of COVID-19 strains monitored by the World Health Organization (WHO).

The Mu variant (pronounced mi) was classified by the entity as a “variant of interest”, for having “a constellation of mutations that indicate potential properties of escape from immunity”, that is, from the protection of vaccines.

However, this suspicion still needs to be confirmed by further studies, according to the organization’s bulletin released on Aug. 31.

This term means that Mu has genetic differences from other known variants and is causing infections in several countries. Therefore, it can pose a specific threat to public health.

In this case, the genetic alterations of the variant can make it more transmissible, responsible for more serious diseases and better able to evade the protection of the existing vaccine. Thus, Mu may be less susceptible to treatments.

In addition, WHO monitors four other variants of interest (VOI): Eta, Iota, Kappa and Lambda.

In order to be considered a variant of concern (VOC), the strain must have proven those characteristics that make it more dangerous and be directly linked to an increase in the number of cases or deaths.

So far, WHO has four variants classified as of concern: Alpha (identified in the UK), Beta (in South Africa), Gamma (in Brazil) and Delta (in India).

Mu, for the time being, continues to be closely monitored to see if it should be reclassified as a VOC.

Coronavirus mutations

The new variant carries important mutations and with the potential for this, either because they are associated with greater transmissibility and reduced immune response, also identified in the Beta, Gamma and Delta variants.

Although there is still no study on the effectiveness of specific immunizers against Mu, it carries at least three mutations that are associated with reduced immunity protection provided by vaccines.

Data being analyzed by the WHO indicate that people who are vaccinated or who have already had COVID may not have as strong protection against this variant, but more studies are needed to confirm this.

However, as these data are from laboratory studies, it is not yet possible to know for sure how the variant actually works in the population.

In a report on variants, the organization also points out that only a new generation of vaccines, which also block COVID transmissions, will be able to prevent new mutations from appearing.

Where did it appear and where has it been identified?

Mu was first identified in Colombia in January of this year, when it received the designation B1621. Since then, it has been detected in 40 countries including the United States, South Korea, Japan, Ecuador, Canada and parts of Europe.

However, it is estimated that currently it is responsible for only 0.1% of infections worldwide.

The variant has been far more prevalent in Colombia than anywhere else. Mu is already the predominant variant in circulation in the country and is responsible for more than a third of the cases of COVID-19.

The third wave of the disease in the South American country, between April and June, has been attributed to this variant.

During that period, when Colombia recorded about 700 deaths a day, nearly two-thirds of the genetic tests carried out on the people who died indicated the presence of the Mu variant, according to the country’s National Institute of Health.

In the United States, about 2,000 cases have been identified so far, according to the Global Initiative on Sharing All Influenza Data (GISAID), the largest database of new sequences of the genome of the coronavirus in the world. Most cases are concentrated in California, Florida, Texas and New York.

However, US officials do not consider Mu an “immediate threat now” in the country, as it is not yet the dominant one. Right now, Delta is the one that worries the most, as it is responsible for more than 99% of cases.

In Brazil, the variant was first identified in July during the Copa America. The samples were collected in Mato Grosso and analyzed by the Instituto Adolfo Lutz, in São Paulo. The positive tests were from a Colombian and an Ecuadorian.

In addition, there have already been two confirmed cases in Amazonas, in the region of Tabatinga, which borders Colombia.

This Tuesday (14/9), the Secretary of State for Health of Minas Gerais, Fábio Baccheretti, mentioned the possibility of community transmission of the variant in the state. So far, the government has confirmed seven cases of Mu, distributed in Braúnas (2), Virginópolis (3) and Guanhães (2) – cities in the Vale do Rio Doce.

Symptoms and Delta still focuses concerns

The new variant appears to have the same symptoms as all the other strains of the new coronavirus: high fever, continuous cough, loss or change in smell or taste are some of them.

They point out that the emergence of variants is expected within the advancing cycle of a virus during a pandemic such as COVID, especially in places where the circulation of this virus is still high. Most mutations have little or no effect on the virus’ properties.

But, in this process, some more dangerous variants emerge and, for now, Delta is the one that raises the most concern in the world, as it has demonstrated a great transmission capacity and has already been identified in about 170 countries.

In the state of Rio de Janeiro, for example, it is considered the predominant variant since August.

What makes Delta more problematic is that people infected with this variant can have large amounts of virus in their upper airways – such as the nose, mouth and larynx – sooner than they would with the original version of the coronavirus, even without showing symptoms.

With a greater amount of virus in the body, a person can transmit it more easily and have their immune system tested harder. Therefore, the variant infects at least twice as much as the original version of the coronavirus.

Furthermore, it is cause for concern that Delta has made progress even in countries with high vaccination coverage. This does not mean, however, that this vaccination coverage has no effect.

The more people vaccinated with two doses or with a single dose immunizer, the lesser the chance of emergence and proliferation of new variants.

(With information from BBC News Brasil)

*Intern under the supervision of the editor Álvaro Duarte

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