Lab medical director explains how COVID-19 testing works
Lab technologists are working around the clock in the Edward-Elmhurst Health system, which is one of 12 sites across the state running tests for the COVID‐19 virus.
The labs have ramped up capabilities since testing began March 22 and now can run a total of 650 tests each day, said Dr. Alvaro Candel, chairman and medical director of the Department of Pathology and Laboratory Medicine at Elmhurst Hospital.
The Daily Herald talked with Candel to better understand molecular testing, as the process of detecting the virus is called, and how it works for patients. Here is an edited version of the conversation.
Q: Who can be tested now through Edward‐Elmhurst Health?
A: Only individuals who are symptomatic, meaning those who have a fever, cough or shortness of breath, and have a doctor's order for the test. Doctors in the emergency departments at both hospitals determine whether patients need to be tested. Drive-through testing at the Edward‐Elmhurst Health corporate center is conducted by appointment only.
Q: How are tests performed?
A: A specimen is collected with either a nasal swab or a nasopharyngeal swab. A nasal swab similar to a Q‐tip is inserted into both sides of the nose. You have to twirl the swab at least five times in each side of the nose. A nasopharyngeal swab is a long thin swab that collects specimen from the back of the nasal passage. It takes around 20 seconds to get a good specimen. It is critical to get a good specimen because if not, that increases the false‐negative rate on these tests.
Q: How are specimens analyzed?
A: The labs use three different testing platforms — one that takes roughly five hours to run batches of up to 94 specimens at a time, and two designed to analyze one specimen at a time and provide results within 15 to 45 minutes. Once a specimen is collected, lab technologists mix it with test reagents and place it into one of the testing instruments. When the reagents interact with the specimen, technologists are able to determine whether the sample has viral RNA that indicates the presence of the COVID‐19 virus.
Q: How are patients notified of test results?
A: Patients who drive up to the corporate center testing facility are notified directly of their results through our call center, typically within 24 to 48 hours. Patients tested in the emergency department typically are notified within one hour of providing the specimen. The quicker testing platforms are used when clinical need requires an immediate determination of whether a patient has the virus, such as in the emergency department, so medical professionals know if the patient needs to be admitted into the hospital and/or placed in isolation.
Q: Why is testing capability limited?
A: One reason for testing being limited is there are not enough nasopharyngeal swabs, which gather specimens from the back of the nasal passage, near the throat. There are also limitations on viral transport media, a liquid that is used to contain specimens collected by nasopharyngeal swabs and deactivate the COVID‐19 virus without destroying the viral RNA. But specifically for Edward‐Elmhurst Health, the main limiting factor is test reagents, which are the materials used to conduct the test. Once the lab gets a swab with a specimen, a lab technologist mixes it with reagents and loads it into a testing instrument. The availability of test reagents is what's limiting us to 650 tests a day.
Q: What is antibody testing and when will it begin at Edward‐Elmhurst Health?
A: Antibody testing, also referred to as serological testing, is used to detect antibodies against the COVID‐19 virus in a patient's blood. Antibodies are developed in response to an infection, so you test for them to see if the patient has been exposed to the virus. The presence of antibodies means that the patient has developed an immune response to the virus. In the case of the COVID-19 virus, we don't yet know if this immune response will protect against re-infection.
Testing terms glossary
Nine terms you need to know to understand the COVID-19 testing process.
Symptomatic: Edward‐Elmhurst Health is only testing people who show symptoms of the COVID‐19 virus, including a fever or cough. Escalating symptoms, defined in part as shortness of breath that worsens over time, should prompt a call to a doctor, a visit to a hospital emergency department or a call to 911.
Molecular testing: This procedure is used to detect the COVID‐19 virus. It involves gathering a nasal or nasopharyngeal specimen on a swab, then testing the specimen in a laboratory, using test reagents to determine whether viral RNA is present.
RNA: A single‐stranded molecule called ribonucleic acid. RNA acts as a messenger carrying genetic information of the COVID‐19 virus to control the creation of proteins.
Nasal swab: Similar to a Q‐tip, these small, dry‐tipped sticks are used to gather nasal specimens to test for the presence of COVID‐19 viral RNA.
Nasopharyngeal swab: Longer and thinner than a basic swab, these sticks reach the back of the nasal passage and are used to gather specimens to test for the presence of COVID‐19 viral RNA.
Viral transport media: A liquid contained inside a long tube that is used to deactivate the COVID‐19 virus without destroying the viral RNA. Specimens taken using nasopharyngeal swabs can be inserted into viral transport media to be tested.
Test reagents: Materials needed to conduct molecular testing for the presence of COVID‐19 viral RNA. Reagents are mixed with patient specimens from nasal and nasopharyngeal swabs and inserted into laboratory testing instruments to produce test results.
Antibody testing: Also called serological testing, this procedure is used to detect the presence of antibodies for COVID‐19 in a person's blood.
Antibodies: Proteins created by the body after exposure to a virus, which is called an immune response. In the case of the COVID-19 virus, doctors don't yet know if this immune response will protect against re-infection.