Nearly 22,000 COVID-19 tests have been performed in Greenwood County as of Sunday and local health officials use different types of tests to meet different needs.
Dr. Chris Oxendine at Abbeville Area Medical Center said the best way to break down test types is by ones used to determine acute infection, which includes PCR and antigen testing, and testing to determine if someone had been previously infected, which is testing for antibodies.
PCR, or polymerase chain reaction tests, are considered the most sensitive tests available and are often used in hospital labs and by the state Department of Health and Environmental Control.
“This takes genetic material from the virus and amplifies it, allowing for the increased sensitivity,” Oxendine said in an emailed statement. “The downside of this test is the turnaround and cost.”
AAMC sends samples for these tests out to be completed by state-approved labs, but Oxendine said the hospital will soon be able to run these tests in-house. Hospital staff uses these types of tests in mobile testing events.
Rapid antigen tests are used for point-of-care testing at AAMC, Oxendine said. These test for specific types of proteins that are part of the virus. While these tests are typically less sensitive than a PCR test, the benefit is the results come quicker and they are less expensive, making them more accessible for clinics, nursing homes and other similar settings.
Antibody tests don’t check if the patient is sick but instead looks to see if they were infected in the past and have since developed an immune response. AAMC will soon be able to run these tests, and in mid-November will be a part of a DHEC and University of South Carolina prevalence study.
“A ‘selection letter’ will be mailed to a random sample of people across South Carolina,” Oxendine said. “If the letter recipient chooses to participate they will come to AAMC and have labs taken at no cost to the patient. This information will be shared with the state.”
At Self Regional Healthcare, staff members are using four different test platforms, but all are PCR based tests, said Chief Medical Officer and Vice President of Medical Affairs Dr. Matt Logan.
Cepheid is a rapid test used mostly for patients being admitted to the hospital, and it yields results in about 45 minutes to 2 hours.
Abbott ID Now is used in Self’s urgent care centers, but once supplies are more readily available, the hospital wants to expand use. The Abbott tests can only be run one at a time, and it’s less sensitive than other test platforms if the patient is asymptomatic, but it yields results in about 15 minutes.
“Since these machines can only run 4-5 tests per hour, it is not appropriate for use in our drive-through testing line,” Logan said in an emailed statement.
When available, Self staff use the Panther test platform for drive-thru testing. It’s a rapid test that allows batches of specimens to be run at the same time, with results sometimes available the same day. The most common test at the drive-thru line, however, is still the DHEC swab. These cotton swabs are sent off to a testing lab, and yield results within two or three days.
“All of the above tests are frequently in short supply in the U.S., so there are days when we must make substitutions based on what we can source at the time,” Logan said. “We do have ability to test for COVID-19 antibodies in the blood, however, testing for antibodies is not appropriate to diagnose acute COVID-19 infection. This is because developing antibodies after infection with COVID-19 takes time and the response is variable from person to person.”
Work is still underway to develop and improve testing platforms, along with the continued work on developing a vaccine for the virus. For now, however, health officials are still recommending hand hygiene, wearing masks and social distancing as the main ways to avoid getting sick or spreading the virus.