The Korean Society for Laboratory Medicine (KSLM) expressed concerns over the increasing number of people purchasing home antibody kits at pharmacies and taking Covid-19 antibody tests.

Home antibody tests are inaccurate and ineffective, and they can evaluate neither a person’s immunity against the Covid-19 virus nor the vaccine’s effect, the KSLM said.

“We hope people do not have any distrust in vaccination and quarantine guidelines because of a misunderstanding of antibody testing,” the KSLM said in a statement on Monday.

According to the KSLM, interpreting antibody test results is still challenging.

Antibodies are a key component of the immune system against Covid-19. Still, researchers have yet to determine scientifically whether or not antibodies protect people from infection and how long they persist, the KSLM said.

For these reasons, antibody testing is used only to determine the scale of the epidemic in epidemiological studies and diagnose past COVID-19 infections in some patients.

“We do not recommend using antibody tests to assess the immunity status of Covid-19 patients,” the society said.

People who have finished vaccination do not have to take antibody testing to find whether they developed antibodies, the KSLM went on to say.

Not only the Korea Disease Control and Prevention Agency (KDCA) and the Ministry of the Food and Drug Safety but the U.S. CDC, FDA, and the European Center for Disease Prevention and Control (ECDC) said it was difficult to gauge whether recipients of Covid-19 vaccines are safe from Covid-19 only with antibody test results.

“Even vaccinated people can show different antibody testing results depending on the type of the vaccine, the type of the antibody test, and underlying diseases,” the KSLM said.

Due to the difficulty interpreting antibody test results and the impossibility of judging the effectiveness of a vaccine based on antibody test results alone, the need for antibody testing for the vaccinated is very low, it added.

The KSLM advised against skipping or changing the schedule for vaccination because of antibody testing results. Some people claim that vaccines are ineffective because antibody testing showed negative results after immunization, but this was far from the truth, the society said.

Home antibody tests are especially unreliable because they were inaccurate and impractical, the KSLM said. Usually, home antibody testing requires many antibodies, and there is a high chance of false-negative results in the early stage of infection, it went on to say. In addition, the home test kits could also react to another virus or various substances incorrectly and yield false-positive results, it added.

For accurate antibody testing, it is best to separate the serum only from the blood.

However, the serum cannot be separated from the self-collected blood, and it is easy to have other substances other than blood, the KSLM said.

For home antibody testing, a physician should read the results within 15 to 20 minutes. Thus, the home testing is almost impractical because a person should collect the sample, take the test, and get a doctor to read the results within 20 minutes, the society emphasized.