Not good.
The delta variant itself. The rapid ascendancy to total domination is the real-world proof that this variant is different. For virologists studying the coronavirus up close, that difference remains somewhat mysterious. Scientists are racing to understand what makes this variant so successful. They are studying it in animal models and in petri dishes, and scrutinizing the genomes of thousands of closely related lineages.
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What’s most sobering to scientists is how the coronavirus keeps getting better at jumping from person to person.
The original strain that emerged in Wuhan, China, had an estimated reproductive number — an “R-naught” — of roughly 2.5. That’s the average number of new infections generated by each infected person in a population without immunity or mitigations. Any number above 1 means that outbreaks will expand and spread. But the CDC and other scientists say delta has a reproductive number greater than 5.
The result is what the United States has endured this summer: viral explosion.
'Sicker quicker'
A nurse checks on a covid patient Aug. 4 at NEA Baptist Memorial Hospital in Jonesboro, Ark. (Houston Cofield/Bloomberg News)
Although the greater transmissibility of delta is clear at this point, scientists are less certain about whether it has enhanced virulence — that is, whether it’s more likely to make a person severely ill. The evidence on disease severity is limited and largely anecdotal.
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Stephen Brierre, chief of critical care at Baton Rouge General in Louisiana, said the onset of respiratory failure requiring ventilation seems to be more rapid: “This is observational and anecdotal at this point: They get sicker quicker.”
Emily L. Tull, a nurse practitioner in the covid unit at Willis-Knighton Medical Center in Shreveport, La., said she is encountering more renal failure, more liver damage and more blood clots in patients since delta took over. More patients are unable to get off ventilators, she said.
Under normal circumstances, one nurse manages two patients in intensive care. In recent weeks, Tull said, “these patients are so sick they’re requiring one-on-one care.”
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Patients are younger compared with earlier in the pandemic, perhaps because fewer young people are vaccinated. Tull said health-care workers are “having to make the decision of do we start dialysis on a healthy 25-year-old?”
In Alabama, where about 43 percent of adults are fully vaccinated and virtually all 67 counties are reporting high levels of community transmission, health officials are seeing inpatient data supporting that “delta may be more harmful,” according to Jeanne Marrazzo, director of the infectious-diseases division at the University of Alabama at Birmingham School of Medicine.
At the 1,200-bed UAB hospital, patients hospitalized for covid-19 are younger, the patients who have died are younger, and there appears to be greater use of a last-resort treatment, called ECMO, that can mechanically substitute for badly damaged lungs. The heavy use of ECMO “connotes truly serious systemic illness,” Marrazzo wrote in an email.
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