QCOSTARICA – All viruses change over time. SARS-CoV-2 has already mutated thousands of times in just under two years. The vast majority of these changes or mutations in genes are insignificant for the management of the pandemic.
However, there are a dozen variants that are of concern to global and local health authorities.
The World Health Organization (WHO) separates them into two groups:
Variants of Interest (VOI)
These are variants of SARS-CoV-2 that meet the following:
- – They have genetic changes that are predicted or known to affect the characteristics of the virus such as transmissibility, the severity of the disease, immune escape, diagnostic or therapeutic escape.
- They have been identified as causing significant community transmission or multiple clusters of covid-19 in several countries, with a relatively increasing prevalence and with an increasing number of cases over time; and / or other apparent epidemiological impacts that suggest an emerging risk to global public health.
There are 5 VOIs: eta, iota, kappa, lambda, mu.
The mu variant is, for now, in the interest group.
Its main ‘home’ is Colombia, according to official data, but it is also present in Costa Rica and in 44 other countries around the world.
Variants of concern (VOC):
They are variants of SARS-CoV-2 that meet the definition of VOI (variant of interest) and that, through comparative evaluation, have been shown to be associated with one or more of the following changes in a degree of importance for the global public health:
- Increased transmissibility or harmful change in the epidemiology of covid-19.
- Increased virulence or change in the clinical presentation of the disease.
- Decrease in the effectiveness of social and public health measures or of available diagnoses, vaccines and therapies.
There are 4 VOCs: alfa, beta, gamma, delta.
Mu variant: another mutation of interest or concern discovered in Latin America
The mu variant was discovered in Colombia in January 2021, and scientists named it B.1.621. On August 30, the WHO classified it as a variant of interest.
As the variants of interest and concern are renamed with letters of the Greek alphabet, this variant is given the name of Mu (the twelfth letter of that order).
In addition to mu (Colombia), other VOIs and VOCs were discovered in our continent: Lambda was discovered in Peru and gamma in Brazil.
Regarding the mu variant, the cases of infections in Colombia caused by this mutation represent 39% of the total number of people sick with covid-19 in that country.
According to official WHO documentation of August 29, these are some details of the variant of interest:
- – Variant B.1.621 classified as VOI on August 30, 2021, and was given the WHO label “Mu”. This includes the descendant lineage Pango B.1.621.1.
- The mu variant has a constellation of mutations that indicate potential properties of immune escape “when the pathogen manages to circumvent – in part or in whole – the antibodies already produced by our body, either after the vaccine or after natural infection. This would eventually increase the risk of infections even with the complete scheme or reinfections “.
- Preliminary data show a reduction in the neutralization capacity of convalescent and vaccinated sera similar to that observed for the beta variant, but this needs to be confirmed by further studies.
- Since its first identification in Colombia in January 2021, there have been some sporadic reports of cases of the mu variant and some larger outbreaks have been reported in other South American countries and in Europe. (…) Although the global prevalence of the mu variant among sequenced cases has decreased and is currently below 0.1%, the prevalence in Colombia (39%) and Ecuador (13%) has steadily increased. The reported prevalence must be interpreted with due consideration of sequencing capabilities and opportunity to share sequences, which vary from country to country.
- More studies are required to understand the phenotypic and clinical characteristics of this variant.
In the United States, the mu variant has already been detected in all states. But the VOC delta continues to represent 99% of covid-19 cases in the U.S.
In the world, at least 46 countries have registered cases of the mu variant.
In Costa Rica, there were at least 26 cases of people infected with the mu variant according to a study of the virus genome dated August 25. This is a small fraction of a weekly study that analyzes between 260 and 400 samples. But it could be on the rise.
As recommended by the WHO, the Costa Rican Institute for Research and Teaching in Nutrition and Health (Inciensa) and the National Children’s Hospital (HNN) will closely follow the evolution of this variant in the country.
Will vaccines work against mu?
As with the other variants, the vaccines approved in Costa Rica (Pfizer and AstraZeneca), and those approved in the United States and Europe, among others, appear to be effective against circulating variants of the coronavirus. Including the mu.
Of course, there is a lack of studies to scientifically corroborate the effectiveness of vaccines against this specific variant, but in the sector, there is confidence based on how the drugs have responded to the other variants in more than a year.
For example, in France, 80% of the people who enter hospitals with covid-19 are people who have not wanted to be vaccinated.
In Germany, 90% of people admitted to intensive care for covid-19 are not vaccinated.
And in the United States, according to official CDC data, 0.0048% of the fully vaccinated people (8,054) in that country the more than 168 million fully vaccinated were hospitalized in August 2021 with covid-19. This is from data during the heyday of the delta variant, and the emergence of variants such as mu and lambda.
In states like California, Delaware, D.C., Indiana, New Jersey, New Mexico, Vermont, and Virginia, the percentage of fully vaccinated people who were hospitalized for COVID-19 in August was zero (0%).
“To date, both real-world data and data from laboratory studies of the vaccine are encouraging, and we do not see evidence that the virus or circulating variants of interest regularly escape protection,” Pfizer spokesperson Kit Longleyhe told the Washington Post.
