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Scientists Hope To Find New Coronavirus Variant In Mass. Before It Spreads Too Far
Angus ChenTwitter
A computer generated image of a coronavirus spike protein like those found on the surface of SARS-CoV-2. (Courtesy David Veesler, University of Washington, and Melody Campbell, University of California San Francisco)
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Traducido por El Planeta Media.
The new SARS-CoV-2 variant, known as B.1.1.7, is probably already in Massachusetts, says Dr. Eric Rosenberg, an infectious disease doctor and director of the clinical microbiology lab at Massachusetts General Hospital. If it's not, he says, it very soon will be.
"If it's not already in circulation in Massachusetts, we know that it's knocking on our door because it's been identified in New York and Connecticut," Rosenberg says.
The first two cases were identified in Connecticut just last week. And if it arrives undetected and uncontrolled, Rosenberg warns, it could become a nasty problem. Rosenberg and his colleague, Dr. Jacob Lemieux, are trying to find the new variant as quickly as possible by screening as many positive coronavirus samples as they can.
The new variant, which was detected in England and has now been found in dozens of countries including the U.S., looks to be more infectious than your garden variety SARS-CoV-2. Lemieux says that means the pandemic might become harder to control if the variant takes off in Massachusetts, and the restrictions the state used last spring to bring cases down may no longer be enough.
"It's not clear that with those measures we would be able to achieve control for a virus that's transmitting at a greater rate. On top of that, we would have to vaccinate a larger proportion of individuals to achieve herd immunity," Lemieux says. "So, this variant is of great consequence from a public health perspective. The sooner we find it, the better."
Scientists first discovered the variant in the United Kingdom last fall, likely as a consequence of the nation's comprehensive genetic surveillance programs, Lemieux says. British scientists sequencing coronavirus genomes noticed that a particular variant was surging rapidly. They called the variant B.1.1.7.
"The prevalence of these B.1.1.7 is increasing more quickly relative to non-B.1.1.7 viruses, and this is happening independently in multiple parts of the United Kingdom," Lemieux says. "That's evidence for increased transmissibility."
That clued scientists into the possibility that this variant is more infectious than the typical coronavirus, and the distinguishing marker of B.1.1.7 may be a mutation on its spike protein – the weapon the virus uses to attack cells.
The mutation is located on a part of the spike that scientists dubbed N501. Scientists at the Fred Hutchinson Cancer Research Center discovered a mutation in this spot is like altering a knife's edge. It can dull the virus's ability to attack, or it can hone its infective potential, making the variant more transmissible.
"So, that's a site of potential biological importance," Lemieux says.
Finding B.1.1.7 early in Massachusetts might help health officials slow the variant's spread. But the only way to definitively identify B.1.1.7 is to sequence coronavirus genomes. That can take several days. Although the Centers for Disease Control and Prevention are scaling up their ability to conduct genomic surveillance, sequencing mass amounts of coronavirus samples to search for and track a variant like B.1.1.7 is outside of the country's capabilities right now, Lemieux says.
"It's the kind of data we're still not yet able to produce in parts of the United States," he says.
But B.1.1.7's mutated spike protein allows scientists to rapidly screen for the variant through other means. One coronavirus test in particular searches for the presence of viral genes, including the genetic code for the spike protein. If someone infected with B.1.1.7 takes one of these tests, it will detect the coronavirus but report a failure to find the spike protein's genetic code.
When that happens at Mass. General Hospital, Lemieux takes that sample and sends it to either a Massachusetts state lab or the Broad Institute for sequencing and, subsequently, identification. Massachusetts, like other states, also sends random samples of coronavirus to the CDC for sequencing.
So far, they've come up dry. B.1.1.7 is still exceedingly rare, at least in the population being tested at Mass General Hospital. Lemieux says that means there's still an opportunity to get ahead of it –- particularly by vaccinating as many people as possible.
"We need to take advantage of this window to roll out the vaccines that we know are effective and encourage people to get the vaccines," he says.
The vaccines, from Pfizer and Moderna, should also be effective against the B.1.1.7 variant, Lemieux says. The more people who are protected from the coronavirus, the more difficult it will be for the pandemic to continue and for dangerous new variants to take hold.
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Angus Chen Twitter Reporter, CommonHealth
Angus Chen was a reporter for WBUR's CommonHealth.