The Mu Variant Should Seniors Be Concerned

The Mu variant is the latest coronavirus mutation to join the World Health Organization (WHO)’s watchlist. (How are we already at ‘Mu’ while we’re still fighting Delta? Because there are many more variants globally than we realize.) Cases of the Mu variant have been found in 49 out of 50 U.S. states, including California, after being detected first in Columbia in January 2021. Mu is on everyone’s radar, while the Delta variant continues to account for more than 99% of U.S. Covid-19 cases, because it has dangerous attributes. Mu has shown an ability to evade antibodies both man-made (monoclonal) and natural (those created by fighting Covid-19 in a recovered patient.) This variant is reducing the protection offered by the vaccine and beating one of the best treatments available for those who get sick. And it’s not the only variant moving around the globe. Seniors and caregivers in San Diego need to know about coronavirus variants and how they work.

First, the good news is that the Mu variant is spreading very slowly in the U.S. and represents an extremely small percentage of new Covid-19 cases here. Currently, Mu variant is most prevalent in South America, Columbia and Peru in particular, showing high rates of transmissibility there. California has reported the most Mu variant cases in the United States with 348 through Labor Day weekend. L.A. County reported 167 of those cases and San Diego has recorded 24 in the same period. Mu’s ability to bypass both monoclonal antibodies and vaccine convalescent antibodies makes it a threat, but its lower transmissibility and severity compared to the Delta variant in the U.S. keep it manageable for now.

On August 30th, WHO named Mu a variant of interest, though the Centers for Disease Control (CDC) hadn’t done so as of mid-September. Global health officials have a system for identifying the threat variants represent, and the CDC’s website explains the three levels this way:

  • A Variant of Interest: “A variant with specific genetic markers that have been associated with changes to receptor binding, reduced neutralization by antibodies generated against previous infection or vaccination, reduced efficacy of treatments, potential diagnostic impact, or predicted increase in transmissibility or disease severity.”
    • Possible attributes of a variant of interest:
      • Specific genetic markers that are predicted to affect transmission, diagnostics, therapeutics, or immune escape.
      • Evidence that it is the cause of an increased proportion of cases or unique outbreak clusters.
      • Limited prevalence or expansion in the US or in other countries.
    • Current CDC Variants of Interest: Eta, Iota, Kappa and B.1.617.3 (which didn’t merit a letter)
  • A Variant of Concern: “A variant for which there is evidence of an increase in transmissibility, more severe disease (e.g., increased hospitalizations or deaths), significant reduction in neutralization by antibodies generated during previous infection or vaccination, reduced effectiveness of treatments or vaccines, or diagnostic detection failures.”
    • Possible attributes of a variant of concern:
      • In addition to the possible attributes of a variant of interest:
        • Evidence of impact on diagnostics, treatments, or vaccines
        • Widespread interference with diagnostic test targets
        • Evidence of substantially decreased susceptibility to one or more class of therapies
        • Evidence of significant decreased neutralization by antibodies generated during previous infection or vaccination
        • Evidence of reduced vaccine-induced protection from severe disease
        • Evidence of increased transmissibility
        • Evidence of increased disease severity
      • Current CDC Variants of Concern: Alpha, Beta, Delta, Gamma
    • Variant of High Consequence: “A variant of high consequence has clear evidence that prevention measures or medical countermeasures (MCMs) have significantly reduced effectiveness relative to previously circulating variants.
      • Possible attributes of a variant of high consequence:
        • In addition to the possible attributes of a variant of concern
          • Impact on Medical Countermeasures (MCM)
          • Demonstrated failure of diagnostic test targets
          • Evidence to suggest a significant reduction in vaccine effectiveness, a disproportionately high number of vaccine breakthrough cases, or very low vaccine-induced protection against severe disease
          • Significantly reduced susceptibility to multiple Emergency Use Authorization (EUA) or approved therapeutics
          • More severe clinical disease and increased hospitalizations
        • Current Variants of High Consequence: (A VoHC would ignore the vaccine and not respond to any of the treatments that work on current strains.)

There are more named variants than we realize, as some of them are impacting other countries and some of them are still revealing their level of threat. Scientists believe that a new variant enters the world every two weeks, but fortunately, we only encounter, classify and label the strongest ones. Viruses are designed for survival, creating copies in every new host. And every copy has the potential for an error, which has the potential to be an infection-enhancing mutation leading to world domination. The best way to prevent new mutations is to not be a new host: get vaccinated, observe safety protocols and stay socially distant.