Context

Kerala government has announced that the state would start conducting ‘rapid antibody test’ on suspected COVID-19 suspects.

About

• Essentially, a rapid test is conducted to determine whether there has been any kind of recent viral infection in a person’s body.
• When a pathogen enters a human body, specific antibodies are released as a response to the virus.
• A rapid test can detect the presence of such antibodies in blood, serum or plasma samples quickly, indicating a viral infection.
• Rapid testing is conducted usually to check for community transmission of a virus during an epidemic.
• According to the health department, it is a simple test that can be done with a person’s blood sample and will give out results within 10-30 minutes. It is also a low-cost test.

How antibody tests are done?

Antibodies are proteins that the body’s white blood cells produce to fight an infection. They bind to a virus, preventing it from infecting a cell, and can remain in blood long after the infection clears. Antibody tests are commonly used to test for exposure to other viruses.

• Antibody tests were particularly effective in finding out if a person who had never shown symptoms had been previously infected by the virus.
• However, these tests could also help in the diagnosis of active cases.
• When patient gets infected at first, he/she make an antibody called IgM. After a few weekes, it gets switched to an antibody called IgD.
• If the tests find IgM, it means the patient has recently got infected.

The story so far:

• So far, India has used the RT-PCR or reverse transcriptase polymerase chain reaction test on nasal or throat swab samples of suspected patients to test for Covid-19.
• The RT-PCR tests look for the presence of the virus in the DNA. They can take anywhere between 12-24 hours to show results.
• In comparison, the rapid antibody tests identify disease-fighting antibodies in blood samples and can deliver results in 45 minutes to two hours.
• However, since antibodies are usually detectable only after around 7-10 days of being infected by the virus, such tests could throw up false negatives – an infected person may appear normal in the blood test.

The rapid tests can be of real help for the state. With these tests, more than double the number of people could be tested for the virus on daily basis and that too on low costs. For sure, this will go a long way in preventing the community transmission of the virus.