The World Health Organization announced it is now tracking a new coronavirus variant known as “mu,” or B.1.621. Early data suggest the variant is showing resistance to COVID-19 vaccines similar to the beta variant, which one recent study suggests is deadlier than all other variants.
Variants of interest usually cause “significant community transmission or multiple COVID-19 clusters, in multiple countries with increasing relative prevalence alongside increasing number of cases over time, or other apparent epidemiological impacts to suggest an emerging risk to global public health."
“The Mu variant has a constellation of mutations that indicate potential properties of immune escape," the global health agency noted. "Preliminary data presented to the Virus Evolution Working Group show a reduction in neutralization capacity of convalescent and vaccinee sera similar to that seen for the Beta variant, but this needs to be confirmed by further studies.”
According to GISAID, over 2,000 cases of mu variant have been reported in the United States. That marks the highest number of all the countries where mu cases were reported.
“Since its first identification in Colombia in January 2021, there have been a few sporadic reports of cases of the Mu variant and some larger outbreaks have been reported from other countries in South America and in Europe. As of 29 August, over 4500 sequences (3794 sequences of B.1.621 and 856 sequences of B.1.621.1) have been uploaded to GISAID from 39 countries,” the WHO report states.
“Although the global prevalence of the Mu variant among sequenced cases has declined and is currently below 0.1%, the prevalence in Colombia (39%) and Ecuador (13%) has consistently increased. The reported prevalence should be interpreted with due consideration of sequencing capacities and timeliness of sharing of sequences, both of which vary between countries. More studies are required to understand the phenotypic and clinical characteristics of this variant. The epidemiology of the Mu variant in South America, particularly with the co-circulation of the Delta variant, will be monitored for changes,” the international health agency added.
Since WHO declared the COVID-19 pandemic in March 2020, nearly 216 million cases of the virus have been reported, and just under 4.5 million people have died.
WHO is tracking four coronavirus variants of concern: alpha, beta, delta and gamma. It is also monitoring five variants of interest, including mu, eta, iota, kappa and lambda,
In a report published in August, researchers from Qatar evaluated the severity, acute-care hospitalization, criticality, ICU hospitalization and fatality of both the alpha and beta variants of the virus through eight case-control studies.
The study came after the Arab nation experienced a severe wave of alpha variant COVID-19 infections beginning in mid-January, which peaked in March. This wave was then immediately followed by the beta variant that peaked in the first week of April.
According to researchers: “The Alpha variant presented a 48% higher risk of severe disease than wild-type variants in the population of Qatar, affirming its greater gravity.”
Data on the beta variant was even more troubling.
“Infection with the Beta variant was associated with even greater risks of severe and critical disease and COVID-19 death, affirming earlier observational analyses suggesting its high gravity. Compared to the Alpha variant, infections with the Beta variant posed a 24% higher risk of severe disease, 49% higher risk of critical disease, and 57% higher risk of COVID-19 death,” researchers said.