Private health labs have begun offering coronavirus antibody testing in an effort to better track the spread of illness in South Carolina communities.
Although antibody tests are not used to confirm new coronavirus cases, health experts believe they can be useful in helping track the extent of infections and may help with developing a vaccine for COVID-19.
Rural Health Services Inc. is providing antibody testing to those who may have been exposed to the coronavirus in the Aiken County community.
What are antibodies?
Antibodies are proteins that form in response to antigens. Antibodies are created by the body to fight off illnesses, including respiratory infections like COVID-19.
Because these antibodies remain in a person's body even after they have fully recovered from sickness, they can indicate whether a person who is currently healthy has previously come into contact with coronavirus, according to Dr. Kenneth Jones, chief medical officer at Rural Health Services.
"We're testing for two types of antibodies in particular for COVID-19," Jones said.
Testing being performed at Rural Health Services is looking for antibodies known as IgG and IgM.
"The higher the level of IgG antibodies, the less likely you may be to get sick again," said Jones.
Antibody tests are not used to confirm new coronavirus cases by the S.C. Department of Health an Environmental Control. Even if an antibody test comes back positive, the agency will not include the result in the state's coronavirus case count.
The primary reason for this, Jones said, is because the antibodies being screened for in coronavirus antibody testing can also form in response to similar illnesses caused by the same family of viruses.
Jones is "pretty positive" the positive results on antibody tests are from COVID-19, which has been surging in several states since May, including South Carolina.
"Even if those tests are not specific for COVID-19, I feel it really is, at this point," Jones said.
Antibodies are also disease-specific, according to the CDC. For example, antibodies formed by a measles infection will not protect a person from getting infected by or recover from mumps.
Antibody testing is used to help reveal a wider scope of the spread of COVID-19 in communities, according to DHEC. The tests can help indicate whether a person who was asymptomatic or was unable to be tested for COVID-19 while previously ill has come into contact with the virus.
The majority of people being recommended for antibody testing locally are patients who have experienced COVID-19 symptoms, such as cough or fever, and did not receive a COVID-19 test at the time, Jones said. The test is intended for individuals who have experienced symptoms or had exposure to a known case a minimum of 10 days prior to seeking the test. Patients should inquire with their health care provider or with physicians at Rural Health Services to determine whether they are recommended for an antibody test.
Drawbacks to antibody testing
While antibody testing can help track the spread of disease in communities, DHEC has expressed some concerns with using antibody testing at all due to patient behaviors.
According to DHEC, receiving an antibody test may cause patients to relax their social distancing behaviors by "thinking they are not infectious" due to their results. But because it takes 1-3 weeks after contracting the virus for antibodies to even begin forming, a patient who receives a negative antibody test could still be infected with COVID-19 and unknowingly be infecting other people. Even if a person tests positive for antibodies, they may still be infectious because their body is actively fighting off the disease.
DHEC is also concerned that people who test positive for COVID-19 antibodies might believe they are immune to coronavirus. There have been several reported cases – in the U.S. and abroad – of people becoming infected with COVID-19 after previously recovering from the illness. The CDC has stated more research needs to be done to determine how much protection IgG antibodies offer from coronavirus.