New COVID Variant Spreading in US, Experts Explain Risks (Or Lack Thereof)
Compared to Eris, BA.2.86 has a significantly lower growth efficiency, meaning that it is less capable of replicating itself in the human body.
The new BA.2.86 variant, unofficially known as Pirola is taking hold in the United States.
Between Oct. 28 to Nov. 25, its prevalence increased from 1 to around 9 percent in the United States, according to the U.S. Centers for Disease Control and Prevention (CDC).
The World Health Organization designated Pirola as a variant of interest on Nov. 21, yet it also found the public health risk posed by BA.2.86 to be “low at the global level (pdf).”
In an update published on Nov. 27, the CDC agreed with the WHO’s assessment “that the public health risk posed by this variant is low compared with other circulating variants, based on available limited evidence.”
Pirola is derived from BA.2, an earlier Omicron variant.
Other variants derived from BA.2 include XBB.1.5 which became the dominant strain in early 2023.
The current dominant variant is H.V.1, and it is derived from the variant EG.5, unofficially known as Eris, a previously dominant variant in the United States.
“At this time, BA.2.86 does not appear to be driving increases in infections or hospitalizations in the United States,” the CDC wrote.
Research outside of the United States similarly suggests that Pirola should not be more severe than current variants.
Researcher Yunlong Cao, who holds a doctorate in physical biochemistry from Harvard found that Pirola “exhibits lower cell infectivity” compared to XBB.1.5 and Eris.
A preprint study from Japan found that while Pirola may be more transmissible than Eris a previous dominant variant, it is less likely to cause disease.
Compared to Eris, Pirola has a significantly lower growth efficiency, meaning that it is less capable of replicating itself in the host, the authors wrote.
“This is not the second coming of omicron. If it were, it is safe to say we would know by now,” Bill Hanage, associate director and professor of epidemiology at Harvard wrote on X on Sep. 1, when the variant’s prevalence was significantly lower.
