The COVID-19 virion has proteins on the surface that assist in its entry into epithelial cells. In a recent Cell article the authors note:
A SARS-CoV-2 variant carrying the Spike protein amino acid change D614G has become the most prevalent form in the global pandemic. Dynamic tracking of variant frequencies revealed a recurrent pattern of G614 increase at multiple geographic levels: national, regional and municipal. The shift occurred even in local epidemics where the original D614 form was well established prior to the introduction of the G614 variant. The consistency of this pattern was highly statistically significant,suggesting that the G614 variant may have a fitness advantage. We found that the G614 variant grows to higher titer as pseudotyped virions. In infected individuals G614 is associated with lower RTPCR ycle thresholds, suggestive of higher upper respiratory tract viral loads, although not with increased disease severity. These findings illuminate changes important for a mechanistic understanding of the virus, and support continuing surveillance of Spike mutations to aid in the development of immunological interventions.
Namely certain mutations may result in more aggressive growth but uncertain virulence. Fauci is quoted in the Hill stating:
He said it is possible this strain carries a higher viral load in the respiratory system, thereby making human transmission more likely. “The data is showing there’s a single mutation that makes the virus be able to replicate better and maybe have high viral loads,” Fauci said. "It just seems that the virus replicates better and may be more transmissible," he continued. The study, which was released by researchers affiliated with the Sheffield COVID-19 Genomics Group, stated Thursday that the new strain "has become the most prevalent form in the global pandemic."
Just what this means in terms of morbidity and mortality is uncertain. However viruses are noted for this type of behavior.
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