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Coronavirus mutations are not slowing down

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During those terrifying early days of the pandemic, scientists offered one piece of reassuring news about the novel coronavirus: It mutated slowly. The earliest mutations did not appear to be consequential. A vaccine, if and when it was invented, might not need regular updating over time.

This proved overly optimistic.

The coronavirus, SARS-CoV-2, has had billions of chances to reconfigure itself as it has spread across the planet, and it continues to evolve, generating new variants and subvariants at a clip that has kept scientists on their toes. Two-and-a-half years after it first spilled into humans, the virus has repeatedly changed its structure and chemistry in ways that confound efforts to bring it fully under control.

And it’s not showing signs of settling down into a drowsy old age. Even with all the changes so far, it still has abundant evolutionary space to explore, according to virologists who are tracking it closely. What that means in practical terms is that a virus that’s already extremely contagious could become even more so.

“This virus has probably got tricks we haven’t seen yet,” virologist Robert F. Garry of Tulane University said. “We know it’s probably not quite as infectious as measles yet, but it’s creeping up there, for sure.”

The latest member of the rogue’s gallery of variants and subvariants is the ungainly named BA.2.12.1, part of the omicron gang. Preliminary research suggests it is about 25 percent more transmissible than the BA.2 subvariant that is currently dominant nationally, according to the Centers for Disease Control and Prevention. The CDC said the subvariant has rapidly spread in the Northeast in particular, where it accounts for the majority of new infections.

“We have a very, very contagious variant out there. It is going to be hard to ensure that no one gets covid in America. That’s not even a policy goal,” President Biden’s new covid-19 coordinator, Ashish Jha, said in his inaugural news briefing Tuesday. ...

No amount of vaccination or boosting can create a perfect shield against infection from SARS-CoV-2. What the vaccines do very well, however, is greatly reduce the risk of severe illness. That is hugely consequential as a matter of public health, as is the wider use of therapeutics, such as the antiviral Paxlovid.

The vaccines currently deployed were all based on the genomic sequence of the original strain of the virus that spread in late 2019 in Wuhan, China. They essentially mimic the spike protein of that version of the virus and trigger an immune response that is protective when the real virus shows up.

But the variants that have emerged can evade many of the neutralizing antibodies that are the immune system’s front line of defense.

“It’s evolving at a fairly rapid rate,” said Jesse Bloom, a computational biologist at the Fred Hutchinson Cancer Research Center in Seattle. “I do think we need to aggressively consider whether we should update vaccines, and do it soon.”

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