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Scientists who work for the US Army. USA They have designed a new Covid-19 test that could identify carriers before they become infectious and spread the disease, The Guardian has learned.
In what could be a significant advance, project coordinators hope that the blood-based test can detect the presence of the virus as soon as 24 hours after infection, before people show symptoms and several days before a carrier considers himself capable of transmitting it to other people. That is also around four days before current tests can detect the virus.
The test came from a project established by the US Army’s Defense Advanced Research Projects Agency (Darpa). USA Aiming to quickly diagnose germ poisoning or chemical warfare. It was hastily reused when the pandemic erupted, and the new test is expected to be submitted for emergency use approval (US) by the United States Food and Drug Administration (FDA) within a week.
“The concept fills a diagnostic gap across the world,” director of Darpa’s Office of Biological Technologies, Dr. Brad Ringeisen, told The Guardian, as he must also fill the gaps in testing at later stages. of infection. If given FDA approval, he said, it had the potential to be “absolutely a game changer.”
While preinfectious screening would improve the efficiency of testing and tracking programs as governments around the world relax the blocks, Darpa cautioned that it should wait until after FDA approval is granted and the test can be put in place to get evidence of how early the virus can pick up.
“The goal of the research is to develop and validate a diagnostic test for early host blood response for Covid,” Professor Stuart Sealfon, who heads the research team at Mount Sinai Hospital in New York, said in an email.
He said the test approach, which looks at the body’s response while fighting Covid-19, should produce results earlier than current nasal swab tests looking for the virus itself. “Because the immune response to infection develops immediately after infection, a Covid firm is expected to provide a more sensitive Covid infection diagnosis earlier,” he told The Guardian.
The research behind the development of the tests will finally be made public, and collaborative teams from Mount Sinai, Duke University and Princeton Medical Schools are expected to publish online, allowing scientists around the world to test similar methods.
If the US is granted, the test should begin to be implemented in the US. USA In the second half of May. Approval is not guaranteed, but Darpa scientists are excited about the potential impact as governments loosen the blockades amid concerns about controlling potential second-wave outbreaks.
“We are all extremely excited. We want to implement this test as quickly as possible, but at the same time share it with others who want to implement it in their own countries, ”said Dr. Eric Van Gieson, who established Darpa’s Epigenetic Observation and Characterization (Echo) program. last year to diagnose victims of biological warfare, and has redirected it to focus on Covid-19. Epigenetics analyzes a set of controls on genes that can respond to the environment.
The hope that the test can detect carriers before they become infectious is based on previous research on other viruses, although Sealfon said this remained “unknown” to Covid-19.
“We have evidence that the diagnosis occurs in the first 24 hours for influenza and an adenovirus,” said Van Gieson. “We are still in the midst of demonstrating that with Covid-19. That said, we should know very soon after the US. “He sees potential for the United States to perform up to a million tests a day, starting with 100,000 daily in May.
The test would increase the possibility of isolating preinfectious cases and closing the transmission chains. It could also dramatically reduce quarantine periods for people exposed to Covid-19 spreaders, allowing them to return to work in a matter of days. “It could be in exceptional demand,” said Chris Linthwaite, executive director of Fluidigm, a California life science technology company that is part of the project, which believes that frequent testing can help manage the workforce as they return to offices, warehouses and factories.
The UK government announced plans two weeks ago to restart a contact-tracking program that was abandoned at the start of the outbreak. Britain’s declared target was 100,000 tests a day in late April. France announced Tuesday that it would evaluate 700,000 people per week, including those without symptoms.
Other countries such as South Korea, Australia and New Zealand already have efficient tracking systems, but would be boosted if carriers were detected early.
Darpa experts also see the potential to improve protocols to protect healthcare workers and others in high-risk jobs, as well as those in relatively autonomous or isolated communities, such as nursing homes and prisons or ships on board.
The test uses the same polymerase chain reaction (PCR) machines that are used to check the nasal swabs of people suspected of having the virus. “It is a simple adjustment,” said Van Gieson. “The infrastructure is already there.”
The limitations of use are similar to those faced by countries such as Great Britain and depend on PCR capacity, chemical reagent stocks and logistics. Results can take an hour or more if samples are to be sent to laboratories.
Like the viral test, the new blood test looks for a type of molecule called RNA. In this case it is messenger RNA (mRNA). “The target mRNA is part of the immune response to viral infection,” said Sealfon. “The levels of mRNA expression really adjust due to the presence of Covid-19. Understanding the immune response is key to fighting Covid-19. “
Covid-19 is believed to incubate for about five days, at which time people are supposed to become infectious. It is also when the virus can be detected by current nasal swab tests. “They do the job, they just don’t tell you that someone is sick until maybe four days after this [new test]”Van Gieson said.
Research shows levels of accuracy greater than 95%. “This is something that will need to be constantly monitored as it will inevitably shift up or down,” said Van Gieson.
Blood samples are more difficult to collect than nose swabs, but can be more reliable. Swab testing can be difficult because it requires taking a sample from the depths of the nose.
“It can throw a lot of false negatives,” said Professor Lawrence Young of the University of Warwick, adding that recent studies showing low reliability were likely due to poor swab sampling. “I have been very concerned about the television images of drive-in tests. Something that can be reliably measured in blood could be a good thing.”
However, like all investigators contacted by The Guardian, he was unwilling to comment further until the team led by Mount Sinai published their investigation. Most were concerned about potential problems with precision and practicality. Blood collection is a potential limitation, as drive-in centers are often not equipped to do this. It takes a milliliter of blood, a fifth of a teaspoon.
The research team is expected to publish the mRNA sequence, allowing others to create the so-called “primer” required. A similar approach was taken when China released the genetic sequence of the virus in January, allowing tests to run rapidly in South Korea and elsewhere.
