A more contagious variant of the coronavirus found for the first time in Britain is spreading rapidly in the United States, doubling approximately every 10 days, according to a new study.
Analyzing half a million coronavirus tests and hundreds of genomes, a team of researchers predicted that within a month this variant could become prevalent in the United States, potentially bringing an outbreak of new cases and an increased risk of death.
The new research offers the first national look at the history of the variant, known as B.1.1.7, since it arrived in the United States in late 2020. Last month, the Centers for Disease Control and Prevention warned that B.1.1 . 7 could become prevalent in March if it behaved the way it did in Britain. The new study confirms this projected path.
“Nothing in this article is surprising, but people need to see it,” said Kristian Andersen, co-author of the study and virologist at the Scripps Research Institute in La Jolla, California. “We should probably prepare for this to be the predominant strain in most places in the United States by March. “
Dr. Andersen’s team estimated that the transmission rate of B.1.1.7 in the United States is 30% to 40% higher than that of more common variants, although those numbers may increase as more data arrives, he said. it. The variant has already been implicated in outbreaks in other countries, including Ireland, Portugal and Jordan.
“In fact, there could be a very serious situation developing in a matter of months or weeks,” said Nicholas Davies, an epidemiologist at the London School of Hygiene and Tropical Medicine, who was not involved in the study. “These may be the first signs that warrant an urgent investigation by public health officials.”
Dr. Davies cautioned that data from the USA is more irregular than that from Britain and other countries that have national variant monitoring systems. Still, he found results from some parts of the United States of particular concern. In Florida, where the new study indicates that the variant is spreading particularly fast, Dr. Davies fears that a new wave may occur even earlier than the rest of the country.
“If these data are representative, there may be limited time to act,” he said.
Dr. Andersen and his colleagues posted their study online on Sunday. It has not yet been published in a scientific journal.
When the British government announced the discovery of B.1.1.7 on December 20, Dr. Andersen and other researchers in the United States began to check it on American coronavirus samples. The first case appeared on December 29 in Colorado, and Andersen found another shortly after in San Diego. It was soon located in many other parts of the country.
But it was difficult to determine how widespread the variant was. B.1.1.7 contains a distinct set of 23 mutations spread over a genome of 30,000 genetic letters. The best way to find out if a virus belongs to the B.1.1.7 strain is to sequence its entire genome – a process that can be performed only with special machines.
The CDC hired Helix, a laboratory testing company, to examine its Covid-19 samples for signs of B.1.1.7. The variant may have a negative result in one of the three tests Helix uses to find the coronavirus. For further analysis, Helix sent these suspicious samples to Illumina to have their genomes sequenced. Last month, Helix contacted Dr. Andersen and his colleagues to help analyze the data.
Analyzing 212 American genomes B.1.1.7, Dr. Andersen’s team concluded that the variant probably first arrived in the United States in late November, a month before it was detected.
The variant was introduced separately in the country at least eight times, probably as a result of people who traveled from Britain to the United States between Thanksgiving and Christmas.
The researchers combined the genome sequencing data with the general results of Helix tests to come up with an estimate of how quickly the variant spread. It has become exponentially more common in the past two months.
In Florida, scientists estimate that more than 4% of cases are now caused by B.1.1.7. The national number can be 1% or 2%, according to your team’s calculations.
If this is true, a thousand or more people can be infected with the variant every day. The CDC recorded only 611 B.1.1.7 cases, attesting to the inadequacy of the country’s genomic surveillance.
In parts of the country where Helix doesn’t do a lot of testing, it’s probably underestimating the spread, Andersen warned.
“It clearly isn’t enough,” he said. “I can guarantee that there are places where B.1.1.7 can be relatively prevalent now that we wouldn’t take it.
Nathan Grubaugh, a virologist at Yale University who was not involved in the new study, says the data makes it clear that the incidence of B.1.1.7 is increasing just as scientists warned it would increase. But he doesn’t think the new study reveals exactly how it is growing. “It doesn’t really reveal the cause at this point,” he said.
It is possible that the B.1.1.7 transmission chains are spreading faster than other viruses. Or it could be that B.1.1.7 was more common among incoming travelers, starting new outbreaks.
“I still think we are weeks away from really knowing how this is going to end,” said Grubaugh.
The contagiousness of B.1.1.7 makes it a threat to be taken seriously. Public health measures that work on other variants may not be sufficient to prevent B.1.1.7. More cases in the United States would mean more hospitalizations, potentially overwhelming hospitals that are only now recovering from a record number of patients in the past month.
To make matters worse, Dr. Davies and his colleagues at the London School of Hygiene and Tropical Medicine posted an online study on Wednesday suggesting that the risk of dying from B.1.1.7 is 35 percent higher than for others variants. The study has not yet been published in a scientific journal.
Communities can take steps to combat variants like B.1.1.7, as Dr. Grubaugh and his colleagues at Yale University recently described in the journal Cell. For example, they said, health officials should reinforce messages about wearing effective masks, avoiding large gatherings and ensuring that indoor spaces are well ventilated.
Scientists have also asked governments to require sick leave for people diagnosed with Covid-19 to prevent it from spreading in the workplace. “These measures can help to significantly reduce transmission in the community,” wrote Dr. Grubaugh and his co-authors.
Vaccination can also be part of the strategy to combat B.1.1.7. In Israel, where the variant is now prevalent, new cases, serious illnesses and hospitalizations have already dropped significantly in people over 65, a group that has received top priority for vaccines.
“What we need to do with current vaccines is to get them to as many people as possible, as quickly as possible,” said Andersen.
Lowering B.1.1.7 will also reduce the risk that the variant will evolve into something even worse. In Britain, the researchers found samples of B.1.1.7 that gained a new mutation with the potential to make vaccines less effective. It is not clear whether these viruses will become common. But they demonstrate that the coronavirus still has a lot of evolutionary space to explore.
“We should expect them to show up here,” said Andersen. “Whatever is true elsewhere, it will be true here as well, and we need to deal with it.”