- Antibody tests, also called serological tests, have usually been the time-tested approach to finding out the presence of a virus in the body.
- They do so by detecting the presence and quantity of antibodies that are produced by the immune system to battle an infection.
- It is an indirect test because it cannot find the virus, but it can determine if the immune system has encountered it.
- Antibodies can show up between nine to 28 days after an infection has set in; by that time, an infected person, if not isolated, can spread the disease.
- Sometimes the antibodies may be produced in response to a closely-related pathogen and sometimes they may not be the right kind to counter the infection.
- These are the factors that can make an antibody test erroneous.
- Antibody tests are fast and relatively inexpensive.
- Antibody tests are portable, can be administered on-site, conducted en masse and give quick answers.
- Antibody tests can be used to gauge the extent of infection in a community or a large group of people who may have had exposure to the virus.
- Two kinds of antibodies result from an infection: Immunoglobulin M and Immunoglobulin G (IgM and IgG).
- In response to an infection, the IgM is first produced within a week of infection.
- Two weeks later, the levels of IgM reduce and are replaced by IgG.
- The latter is a longer-lasting antibody and, depending on the infectious agent involved, can offer different durations of immunity.
- Rapid antibody tests can also play a role in determining the degree of “herd immunity” in a population.
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- In an RT-PCR test, a nasal or throat swab is taken from a patient suspected of having the disease.
- The test involves extracting RNA or ribonucleic acid, the genetic material of the virus, and checking if it shares the same genetic sequence as the SARS-CoV-2 virus.
- If it is a match, the sample is deemed positive.
- The only way such tests turn negative is if the actual sample does not have the virus or the swab was not properly administered and too little of the virus was gleaned.
- The RT-PCR tests began to be followed as the ‘gold standard’ in detecting the virus.
- The current RT-PCR technology requires RNA extracting machines, a specialized laboratory, and trained technicians.
- And at least a minimum of 30 samples are needed to make the process economically viable.
- The tests are done in batches and it can take up to four hours to confidently test for the presence of a virus from a batch.
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