The new coronavirus test for antigens works by detecting protein portions of the virus. Not only can the rapid test yield results within two to 15 minutes, but so far, it also has a 100% success rate in identifying people who are infected.
According to Dr. Gili Regev-Yochay, Director of the Infectious Disease Epidemiology Unit at Sheba, about 300 people have already been screened using the new tests, which were bought from Europe and Korea. An American version of the testing kit is also available, but Sheba does not have access to it yet.
At present, the trial is being conducted on doctors and other staff who work at Sheba’s Department of Emergency Medicine, enabling them to come to work. Otherwise, they would be required to quarantine at home after exposure to the virus, while waiting for test results.
For control purposes, a polymerase chain reaction (PCR) test is performed simultaneously. The PCR test amplifies DNA exponentially by repeatedly doubling the number of molecules. The new tests are quicker and cheaper than PCR tests, and they do not require any special technological devices. However, they must be performed by skilled personnel because they depend on swabbing. A saliva-based antigen test is currently under development, which could be done at home.
The current antigen test is done by inserting the swab with a sample from the patient into a test tube with fluid. Then, an extract of the liquid is placed on a test strip (similar to how a home pregnancy test is done), and an immediate answer is given. A single stripe is negative, while two stripes is positive. According to Dr. Regev-Yochay, the tests are expected to become available on a larger scale within weeks.
Three types of testing for coronavirus are now available: PCR swab tests, serological or antibody tests, and antigen tests. It can take between two and 12 hours to receive results from PCR tests, which cost about three times as much as antigen tests. Antibody tests are used to screen for immunity.
“I really think this is going to make a change in the way we can handle the pandemic,” Dr. Regev-Yochay said. She envisions implementing these tests in schools in “red cities.” First, serological testing would be used to determine if a high percentage of students possess immunity. If so, then the rest of the students could take a rapid antigen test before heading to class in the morning.
