Alarms sounding worldwide for the Mu variant

The declaration by the World Health Organization (WHO) as variant of interest “Mu“to the lineage of the coronavirus identified for the first time in Colombia This week the alarm was raised in Latin America and, although the Delta He continues to be the most predominant and the most worrying one in the world, specialists stressed that “you have to watch Mu’s information closely and see how it interacts with others circulating in the country.”

“Right now, the Delta variant continues to be the one of greatest concern in the world; she was responsible for dramatic situations such as the health crisis in India; it has spread to hundreds of countries and has moved the circulating virus to where it entered. generating new waves, ”virologist Humberto Debat told Telam.

Debat, which is part of the Argentinian inter-institutional genomics project SARS-CoV-2 (PAIS), recalled that “there is ample evidence that Delta is the most transmissible variant, it doubles hospitalization rates, while vaccines are less effective in protecting us from contagion of this variant, although the levels of coverage in severe cases remain very high ”.

However, he explained that we have to be attentive to what is happening with the Mu “because as we have seen in previous waves, the variant landscape at the Latin American level has had a big impact on Argentina” .

“Seeing that to date Mu represents 14% of cases in Chile (which had a variant scenario very similar to ours), this implies that there is a probability that it will enter our country and increase its frequency”, Debat analyzed.

On August 31, WHO published its weekly epidemiological update report in which it reported having incorporated as a variant of interest the B.1.621 line first identified in January in Colombia, which it designated by the letter Greek Mu.

“The Mu variant it has a constellation of mutations that indicate potential immune evasion properties. Preliminary data presented to the Virus Evolution Working Group shows a reduction in the neutralizing capacity of sera from convalescent and vaccinated patients similar to that observed for the Beta variant (identified in May 2020 in South Africa), but this needs to be confirmed by studies. studies. additional, ”the agency said in the document.

In this sense, Debat said that “what has been said by the WHO, which the same organization has indicated needs to be reconfirmed and is not yet in any scientific publication, is a big red flag because Beta is the variant with the greatest escape or immune escape.

According to the WHO, “although the global prevalence of Mu variant among the sequenced cases, it has decreased and is currently less than 0.1%, the prevalence in Colombia (39%) and Ecuador (13%) has steadily increased ”.

“We also know that it represents 14% of cases in Chile; that is, recently it has started to spread to different countries in Latin America and increase its frequency; it is not less because the replication in other regions implies that it is independent of the conjuncture and then it is a ‘property’ of the virus “, described the virologist.

For her part, biochemist Josefina Campos, coordinator of the Anlis-Malbrán genomics and bioinformatics platform, said that “it is difficult to say which variant should cause the most concern in Argentina because the behavior of each will depend on many factors, including how interacts with the variants that are circulating. “

“The Delta it is the majority in the world and it is more likely to enter, but we will have to see how this relationship is established, which is dynamic, “he added.

Regarding Mu, Campos indicated that there is still little data, but we know that it has become very widespread in Colombia and Ecuador, so “we must take into account that what we see are the information on the sequences it shares but not us knowing what the methodology of this surveillance looks like. ”

In principle, both in Colombia and Ecuador, “the Delta it’s very low, but it would be hasty to say that it is the result of the way they competed, we will have to wait a bit to see what happens when they live in the same territory “.

According to data from the latest report from the Ministry of Health on epidemiological surveillance in the country, carried out by the PAIS project and the Anlis-Malbrán, the most common variant in Argentina is Gamma (defined as worrying by the WHO and identified for the first time) once in Manaus, Brazil) with a percentage close to 60% of the samples.

It is followed by Lambda (defined as of interest and said Andean) with approximately 20%; while the Alpha (UK) does not reach 10%.

“What is today the Mu variant was already detected in August in sporadic cases in the city of Buenos Aires, in some travelers and two or three unrelated cases; it was found as part of the systematic surveillance carried out in the city ”, Mariana Viegas, researcher at Conicet and coordinator of the PAIS project, indicated.

However, he stressed that to say that there is community circulation of a variant “it must be systematically detected over time and there must be a risk that the population will acquire it in the community, which is not. not yet the case with Mu “.

For his part, Campos said that the Malbrán had detected the line which is now called Mu in April and “had already observed the constellation of mutations which were of marked interest”.

Another news this week was the public announcement by South African health authorities that they were monitoring a new variant, “C.1.2”, which has yet to be classified by the WHO.

“This is a variant that has a large number of mutations: only in the protein Spike it has more than 12 and in total it has about 59 mutations compared to Wuhan (China); so this is one of the versions of the virus most different from the reference one, but the good news is that you don’t see any distinctive epidemiological behavior, ”Debat described.

The specialist said that “so far it does not extend geographically or chronologically” and that “worldwide only 101 samples have been reported”.

Finally, Campos recalled that “having the greatest amount of population with the two doses is what will allow us to better face the variant. Delta in case it starts to have majority community circulation ”.

“Most vaccines have been shown to offer very good two-dose protection against Delta to prevent hospitalizations and death,” he concluded.