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Hospitalizations for Covid-19 in the United States are on the decline after reaching record levels this month – a welcome sign that the winter surge may finally stabilize. But as new, potentially more contagious variants of the virus circulate, coronavirus modelers warn that the United States is by no means out of the woods yet.
The emergence of new variants isn’t all that surprising, but experts say without a better understanding of how these strains affect things like transmissibility and effectiveness of existing vaccines, it’s unclear how. the pandemic can unfold.
“There is so much in the air, and the new variants have thrown a huge monkey wrench into our ability to model things,” said Dr Jeanne Marrazzo, professor of medicine and director of the infectious disease division. at the University of Alabama. in Birmingham. “All of these things make the crystal ball very cloudy.”
Although hospitalizations and the number of new infections in the United States have both declined from the previous seven days, deaths from Covid-19 continue to rise. The country passed 400,000 deaths this week and set a daily record Wednesday, with 4,131 deaths reported, according to an NBC News tally.
It is estimated that the coronavirus has undergone thousands of mutations since its detection in humans. Many ended up being unimportant, but scientists are worried about any alterations that could make the virus more contagious or make available vaccines less effective.
Evidence from the UK has shown that such a variant, known as B.1.1.7, spreads more easily from person to person, although it does not appear to make people more ill and appears to be sensitive to vaccines. A report released last week by the Centers for Disease Control and Prevention said the British variant could become the predominant strain in the United States by March.
New variants have also been reported in South Africa, Brazil and the United States, with a wave of research underway to characterize the changes. Early laboratory experiments suggest that vaccines made by Pfizer and BioNTech and by Moderna may be less effective against the variant identified in South Africa, but research has not been performed in humans and results have not yet been peer reviewed.
As variants emerge, it will be crucial to adhere to measures to slow the spread of the virus and speed up the pace of vaccinations to prevent all those numbers from skyrocketing, said coronavirus modeler Alessandro Vespignani, director of the Network Science Institute. from the University of the Northeast.
That’s because a more contagious variant is likely to lead to more cases overall, which adds even more strain on already overburdened health systems.
“It’s a bit of a race against the emergence of new strains that are more transmissible,” Vespignani said. “If we deploy the vaccine quickly enough and keep the epidemic levels low, that will also slow down the variants and save us more time.”
Vaccine distribution has been problematic, with some states running out of supplies while others have struggled to administer all of the doses they were receiving.
And there are fears that the United States is not doing enough to track genetic changes in the virus by sequencing the genetic codes. Not knowing precisely which variants are present in the country makes it more difficult to protect those at risk, said former CDC official Ali Mokdad, professor of global health at the University of Washington. It also makes it more difficult for modelers to predict how the pandemic might unfold.
“If we don’t stay on top of what’s going around, we might have a local variant that’s more transmissible than the one we’ve seen in the UK, and we won’t know,” he said.
Mokdad is part of the Institute for Health Metrics and Evaluation at the University of Washington, which has developed one of the most cited coronavirus models. Its current projection shows that if the number of new infections declines in the United States, Covid-19-related deaths are not expected to peak until early March.
Still, Mokdad said, there are ways for the United States to avoid further spikes in hospitalizations and deaths, even with the emergence of new variants.
“We have to do what we know to be effective – socialize and wear a mask,” he said. “We can’t celebrate prematurely, because if everyone assumes the worst is behind us, that’s when we’ll see highs again.”
And although models predict that deaths will continue to rise for several weeks, it is possible to flatten the curve if people remain vigilant, Vespignani said.
“Every forecast is not a deterministic outcome,” he said. “We can do something to change the course.”
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