Mutation in dominant Arizona coronavirus strain may make it more infectious
Arizona Republic
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Over 90 percent of novel coronavirus samples from Arizona in a recent genetic analysis have a mutation that researchers hypothesize makes the virus more infectious.
So far, researchers have analyzed more than 1,400 samples of the virus from patients with COVID-19 and have identified a mutated strain that they believe could help explain the recent explosion of cases in the state.
This genetic mutation affects the spikes on the outside of the virus that the virus uses to attach to and infect host cells.
Because of the mutation's crucial location, it could change the way the spikes operate to infect people, making the virus more transmissible, according to David Engelthaler, co-director of the Translational Genomics Research Institute’s Pathogen and Microbiome Division.
"That might be why it's become the dominant strain that has really moved through Europe and the Americas and certainly what we see here in Arizona," he said.
This mutated strain of the virus is the same one that researchers first identified in April as the dominant strain in Arizona and seems to have originated in Europe. Researchers initially thought that this strain was no more infectious than other strains, but was merely dominant due to chance.
However, given additional data, researchers now believe this strain behaves differently than others.
"The earlier strains that came into Arizona didn't have this mutation and those strains didn't go on in most cases to cause any type of sustained outbreaks," Engelthaler said. "They typically fizzled out."
The mutation itself is called the D614G mutation, which Dr. Anthony Fauci acknowledged as seeming to improve the virus's ability to replicate.
The next important question is whether this more-spreadable strain is just as deadly as others.
In an interview with the Journal of the American Medical Association’s Dr. Howard Bauchner, Fauci said, "We don’t have a connection to whether an individual does worse with this or not; it just seems that the virus replicates better and may be more transmissible.”
In the interview, Fauci cautioned that researchers still need to confirm these theories and analyze the mutation further.
Engelthaler thinks this mutation could be making the virus less deadly.
"It's really hard to directly link the fatality rate to the strain of the virus," he said. "But I think there's more evidence that the fatality rates are dropping."
According to data released by the Arizona Department of Health Services, there had been a total of 14,796 confirmed COVID-19 cases and 802 COVID-19 related deaths in Arizona by May 15, when Gov. Doug Ducey's stay-at-home order expired. This translates to roughly a 5.4% death rate from the virus in the state.
As of July 9, there have been a total of 112,671 confirmed COVID-19 cases and 2,038 COVID-19 related deaths statewide, translating to about a 1.8% death rate from the virus.
However, this decreased fatality rate could be because of increased testing statewide, which has allowed the state to better track the total number of coronavirus cases, whereas early numbers may be more likely to only reflect more severe, hospitalized cases.
More cases also are now confirmed among younger patients, who typically have a lower fatality rate.
On May 15, people age 20-44 accounted for 39% of all confirmed cases in Maricopa County. As of July 9, they accounted for 53%.
However, Engelthaler pointed out that the death rate within higher risk age groups has been falling as well. According to Maricopa County's data, about 17% of those who had the disease and were 65 or older died as of May 15. Today the death rate among those infected within that age group hovers around 10%.
"We can't necessarily say that it's directly related to any specific mutations yet in the virus," he said. "But right now, there certainly is an association."
However, he stressed that this doesn't mean the state should relax precautions against transmissions.
"We still need to do everything we can to protect those at most risk," he said.
It's also important to continue to keep track of virus mutations and try to better understand this spike protein mutation, because any mutations could have a big impact on how effective potential vaccines or treatments are.
In particular, since many vaccines and therapeutic drugs are targeting the spikes on the outside of the virus, any harmful mutation on the spike protein could render vaccines useless.
So far, no mutations, including this one, have been found to interfere with vaccine development that is underway, according to Engelthaler.
"We can't say for sure whether or not mutations will cause a negative effect for these vaccines," he said. "But there's no evidence right now to indicate that they would have a negative impact or that the vaccines wouldn't work."
Each time a virus infects a new host, it has another opportunity to mutate. Since this new coronavirus has had the chance to move rapidly across the globe, Engelthaler said it's likely that this will create multiple versions of this virus.
These different versions may have different characteristics or may not all respond to the same vaccines or treatments.
"Hopefully with vaccines, we can whittle those down and just knock down the total amount of transmission," he said. "I think trying to get it to completely go away is certainly not within reach right now, even with a good vaccine program."
In addition to mapping out a genetic family tree of the novel coronavirus so that researchers can better understand and research the various strains, TGen will use their genetic analysis to improve the accuracy of the state's COVID-19 contact tracing efforts.
Engelthaler said TGen hopes to better understand how different strains of the virus are spreading so that they can better limit transmission.
"The virus itself is going to tell us what we need to focus on," he said. "And clearly what we're seeing now is this particular mutation is dominant and will likely remain dominant."
Amanda Morris covers all things bioscience, which includes health care, technology, new research and the environment. Send her tips, story ideas, or dog memes at amorris@gannett.com and follow her on Twitter @amandamomorris for the latest bioscience updates.
