Is a variant worse than Delta on the way? Viral evolution offers clues.
Somewhere in India last October, a person—likely immunocompromised, perhaps taking drugs for rheumatoid arthritis or with an advanced case of HIV/AIDS—developed COVID-19.
Their case might have been mild, but because of their body’s inability to clear the coronavirus it lingered and multiplied. As the virus replicated and moved from one cell to another, parts of the genetic material copied itself incorrectly. Maybe the person lived in a crowded home or went out to buy food in a busy market, but wherever it happened, the altered virus was spread to others. Experts believe this singular situation in one individual is likely how the Delta variant now wreaking havoc in the U.S. and around the world was born.
In the course of the COVID-19 pandemic, thousands of variants have been identified, four of which are considered “variants of concern” by the World Health Organization—Alpha, Beta, Gamma, and Delta, all closely tracked by scientists on websites such as GiSAID and CoVariants. Delta is by far the most contagious—some 97 percent more sothan the earliest circulating virus, according to European researchers. But is it the worst the world might see? Understanding how mutations develop can help us grasp whether more concerning versions may yet appear.
That turn of events in India—or others that may come in other places—was expected by microbiologists who study viruses, although they could not have predicted where it would happen, exactly when, and which lines of genetic code would shift inside the germ. “Every single time the virus gets in a cell it replicates its genome so it can spread to other cells, and this has the potential to make an error,” says Bethany Moore, chair of the microbiology and immunology department at the University of Michigan.
https://www.nationalgeographic.com/science/article/is-a-variant-worse-than-delta-on-the-way-viral-evolution-offers-clues