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What We Know about WHO’s Latest ‘Variant of Interest’

Delta remains overwhelming majority of COVID-19 cases in U.S. and globally, but Mu has emerged as variant of interest

September 08, 2021

The emergence of new COVID-19 variants reinforces the importance of limiting the spread of the virus through vaccination and other precautions, the world’s leading public health officials said today.

Last week, the World Health Organization (WHO) listed the Mu variant as a “variant of interest” and said more research was needed to understand its ability to escape immunization protection and overall transmission.

During a briefing today, officials with the WHO stressed COVID-19 vaccination and other public health precautions can limit the spread of the virus and reduce its ability to mutate.

“The emergence of variants is really coming from where transmission is most happening,” said Kate O'Brien, director of the Department of Immunization, Vaccines and Biologicals at the WHO. “And transmission is most happening where people are unvaccinated.”

Here are a few key takeaways about the Mu variant:

First identified:  Colombia, January 2021

Formal name:  B.1.621

Status:  Last week, the WHO listed Mu as a variant of interest, meaning it has genetic changes impacting “its transmissibility, disease severity, immune escape,” and has caused significant community transmission or multiple COVID-19 clusters

Where it is spreading:  Mu represents less than 1 percent of cases in the U.S. and has declined globally. Cases have consistently increased in Ecuador and Colombia, the WHO said last week. About 2,400 cases have been reported in the U.S., including 38 in Pennsylvania

Vaccine effectiveness:  Last week, the WHO said the Mu variant has “a constellation of mutations that indicate potential properties of immune escape.” Further studies are needed to understand the vaccine’s effectiveness against the virus

Quotable:  “We have to remain vigilant and do what we can to not only get vaccine equity around the world, but to ensure that we stop this virus from circulating as much as we possibly can,” said Dr.Maria Van Kerkhove, COVID-19 technical lead for the WHO

The Centers for Disease Control and Prevention has classified the Alpha, Beta, Gamma, and Delta variants as “variants of concern,” based on their transmissibility, severity of symptoms, and treatment options. More information about variants is available online.

HAP will continue to monitor the latest COVID-19 public health developments and provide updates to members.

For more information, contact Robert Shipp III, PhD, BSN, RN, NEA-BC, HAP’s vice president, population health and clinical affairs.