Washington – A new type of test to detect the coronavirus It offers a faster and cheaper way to detect infections, which would move towards a mass analysis, which according to experts is essential so that millions of people can return to school and work.
But the first so-called antigen test – announced Saturday by the Food and Drug Administration (FDA) – isn’t exactly the type that top government health officials wanted. It is less accurate than the current testing standard, and can only be applied in specialized equipment.
“It is too early to say,” said laboratory researcher Patricia Simner of Johns Hopkins University, evaluating its impact. “It certainly has the potential to aid in the more widespread application of testing.”
Some questions and answers about the new test:
What is different about this test?
The Quidel Corp. test detects new infections but in a different way. Look for traces of virus proteins, called antigens. The same technique is used in rapid tests to detect flu, strep throat, and other infections, which are applied in the hospital or doctor’s office. They represent a solution with advantages and disadvantages: some precision of the most rigorous tests is sacrificed in exchange for faster results and at a lower cost.
“They allow you to dramatically expand the tests and they are very cheap,” Dr. Scott Gottlieb, a former FDA commissioner, said in an interview with CBS on Sunday. But he recognized that the antigen test is less accurate: “They won’t detect COVID in some infected patients.”
Previously, the only way to diagnose active infections was through a test that detects the genetic material of the virus. Although very accurate, most of these tests take hours to yield a result on machines that are primarily found in commercial laboratories, hospitals, or universities. Abbott Laboratories manufactures a 15-minute version of the genetic test that examines the sample on its portable machine, but can only check one sample at a time.
Why is it important to detect the antigen?
The United States is still struggling to increase the volume of tests to levels that most public health experts consider essential. Researchers from Harvard University have predicted that the country needs to be able to do 900,000 tests a day in order to track new cases and contain new outbreaks while reviving its economy. That’s more than triple the nation’s current daily testing rate of approximately 275,000.
White House adviser on the subject, Dr. Deborah Birx, and other federal officials have said a “breakthrough” in antigen testing could clear the way for daily tests before returning to work or school. .
The National Institutes of Health is spending $ 1.5 billion on actions to develop highly efficient and easy-to-use tests that could be applied without professional supervision or special equipment. Although it is an important step in that direction, the Quidel test is not yet at that level.
How does it work?
The new test uses a nasal swab just like other screenings, and the results are ready in about 15 minutes.
The sample is placed in a tube with detection chemicals and then in a cartridge that is inserted into the company’s electronic reading device. There he is exposed to a test strip containing antibodies created in a laboratory. If the antigens and antibodies interact, the test is positive.
How accurate is the test?
The new test is expected to detect about 80% of active COVID-19 infections, according to the FDA. That accuracy rate is similar to other rapid antigen tests for seasonal influenza.
“They are going to detect fewer people than are infected,” said Simner of the UJH. “That’s where you see a lot of skepticism about using antigen tests for the diagnosis of COVID-19.”
For now, Simner and other experts say negative test results for people with symptoms should be confirmed with the more accurate genetic test.
“But as you might imagine, that is not a perfect scenario, because you have to do twice as many tests when the result is not positive,” said Dr. Robin Patel of the Mayo Clinic.
Whats Next?
Many companies are working on versions that would be more accurate, easier to use, and more suitable for mass application.
OraSure Technologies has a $ 700 million federal contract to develop a saliva antigen test that could be applied at home. The company has antigen tests for other viruses – including HIV and Ebola_, which have an accuracy rate of over 95%. Along with precision, the company is focused on speed, as it wants to generate results in 20 to 30 minutes.
“If you’re going to test people who come to work, you can’t make them stand in line at 3 in the morning,” said Stephen Tang, CEO of OraSure. “You need to be able to get their results quickly.”
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