How is the antibody test for the novel coronavirus performed? And what is the possible interpretation of its results?
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| Coronavirus |
When accurate antibody testing for the novel coronavirus becomes widely available, it will help determine the number of people who have been infected with and recovered from COVID-19, including those who were asymptomatic.
Antibody Testing for the Novel Coronavirus
An antibody test for the novel coronavirus, also known as serological testing, is a test for immune proteins in the blood called antibodies. The body produces these antibodies to fight infections and pathogens, such as the novel coronavirus. This is similar to what happens when the body receives a vaccine, such as the flu vaccine, which helps build immunity against the virus.
The antibody test aims to show whether a person has been infected with the virus in the past and whether their immune system responded to it, indicating whether they have recovered or are still contagious. Antibody testing for the novel coronavirus cannot, by itself, determine if the virus is still present in the body at the time of the test, which is why it differs from a diagnostic COVID-19 test.
How to perform an antibody test for the novel coronavirus
A specialist will take a blood sample, usually by pricking the finger or drawing blood from a vein in the person's arm. The sample is then analyzed to check if the immune system has produced antibodies to fight and eliminate the virus. This test looks for one or two types of antibodies to the novel coronavirus, including:
IgM antibodies: These are formed early in the infection.
IgG antibodies: These take longer to form, appearing in most people about 14 days after the onset of symptoms. They usually remain in the blood for a long time after the infection has cleared, but the exact duration of antibodies to the novel coronavirus is not yet known.
Results of Antibody Tests for COVID-19
A positive result for COVID-19 antibodies means the person was previously infected with the virus, even if they didn't experience any symptoms. This is because asymptomatic infection is possible. However, there is a possibility of a false positive result if the antibodies are from an infection with a different type of coronavirus, such as those that cause the common cold.
The presence of antibodies to COVID-19 may offer some protection against reinfection. However, it is not yet known how much protection antibodies provide or how long they last. Therefore, it is essential to continue protecting yourself and others, as reinfection is possible. Always wear personal protective equipment (PPE) if your job requires it.
A negative result may indicate that you have not been infected with COVID-19, but you may have recently been exposed to the virus and have a current infection. The test is still negative because it usually takes one to three weeks after infection for the body to develop antibodies. This means you could still be contagious.