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A coronavirus variant that is thought to be more contagious was detected in the United States in Elbert County, Colo., not far from this testing site in Parker, Colo. The variant has been detected in several U.S. states.
Michael Ciaglo/Getty Images
Michael Ciaglo/Getty Images
Now scientists say the virus is already here in the U.S., and circulating widely— albeit at very low levels, says computational biologist Trevor Bedford at the Fred Hutchinson Cancer Research Center.
«A rough estimate, for across the U.S., would be a frequency of about 1 in 1000,» he told NPR last week. «So about 1 in every 1000 COVID infection is due to the variant.»
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Bedford expects that percentage to rise quickly. In England, B.1.1.7 took about three month to take over and become the dominant strain in the outbreak. Scientists believed the variant first emerged in September. By December, it had become the dominant version in London.
«So I roughly expect a similar timeline of three months, from the variant’s initial arrival in the U.S. in December to starting to dominate the virus population around March,» Bedford said.
How dangerous is the new variant?
With cases already surging here in the U.S., having this new variant dominant outbreak could be very problematic, researchers say. It could fuel another surge on top of the already staggering surge the country is struggling to stop.
Hospitals are packed and health care systems are overstretched across the country with a less transmissible version of the virus. What’s going to happen if a more contagious form starts to circulate widely, even dominate the outbreak?
Right now scientists don’t believe the new variant is more deadly. But its increased transmissibility could, in the end, be even more dangerous, resulting in a much higher number of deaths, says Hodcroft.
«Perhaps counterintuitively, I think that increased transmissibility is probably the worst of these two scenarios, because if something is more transmissible, then you just get it into a larger population,» she says.
One study suggests a person sick with the older version of the virus infects about 10% of their contacts, while a person sick with the new variant infects about 15%. So the new variant increases the transmissibility by about 50%.
To understand the impact of that, remember, viruses spread exponentially. Case numbers grow faster and faster. They accelerate.
«If you then crank that exponential growth up to a steeper curve, you very quickly start infecting many, many, many more people than you would have beforehand,» Hodcroft says. «And even though the percentage of people that end up in hospital or dying stays the same, a small percent of a big number is a big number.»
Small increases in infectiousness cause outbreaks to grow much more rapidly— and to much larger numbers. During the fall surge, each infected person infected about 1.3 other people, on average, Bedford says. Studies suggest the new variant raises this value by about 0.5, so that each sick person could infect 1.8 people, on average.
Two months to prepare
According to Bedford, the U.S. still has about two months to prepare for — and slow down — the variant. On the surface, that timeline sounds like good news. But, the findings are worrying, Bedford says. They mean the steep rise in cases and hospitalizations that is already happening in some states can’t be blamed on a more contagious virus.
«I think it’s not at all really conceivable that this more transmissible variant has contributed to surging cases in the U.S. this fall and winter, » he says. «We’re kind of just barely getting started with this variant.»
Yet the outbreak in the U.S. is the worst it’s ever been. The U.S. reported its most deadly day of the pandemic on Tuesday, with a record 4,327 people dying of COVID-19. Each week, more than 1.5 million people test positive for the virus across the country. Several states, like California, Arizona and Rhode Island have some of the highest infection rates in the world.
The U.S. needs to be thinking about how to minimize damage from this new variant, right now, Hodcroft says. «This is our early warning. Because by the time you have something spreading exponentially in your country, it is much harder to get it under control.»
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What needs to be done will be different for each community. Activities that seemed relatively safe before — like outdoor dining — might not be as safe with the new version of the virus.
Communities should start thinking about acquiring better masks or suggesting to people ways they can improve their masks.
Cities and states can ramp up testing and contact tracing. They can start contact tracing the variant to try and slow down its spread. And finally, the entire country needs to focus on vaccinating people as quickly as possible.
Otherwise Bedford says, in March we will likely see another wave of the virus.
«I was expecting that by around March, things would be getting decently under control in the United States,» he says, because the weather would warm up and more people would be immune, through the vaccine or natural exposure.
«Those factors will bring the previous version of the virus under control,» he says, but not the new variant. «My expectation now is that we end up with a spring wave of this new variant virus.»
- exponential growth
- UK variant
- coronavirus variant