Studying SARS-CoV-2 variants that caused local surges in cases and stoked fears of wider spread but that fizzled out could provide insight into what makes a variant successful, the New York Times writes.
It notes that variants like Gamma, Iota, and Mu arose amid concerns they would spread but, unlike variants like Delta or Omicron, did not do so. Mu, for instance, spread quickly in Colombia and harbored a number of mutations that researchers found alarming, including ones that appeared to enable it to better evade the immune system, the Times says, but once it reached beyond South and Central America, it did not circulate as widely as feared. That could be in part due to that, once there, it had to compete with the Delta variant, underscoring that the context of a variant's emergence can affects whether it goes global.
The fizzled-out variants can also help identify holes in SARS-CoV-2 surveillance, the Times adds. It notes that the Mu variant arose in a part of the world with patchy viral genomic surveillance and further had a frameshift variant that databases initially marked as an error, delaying the release of data on the variant.