Difference Between Antibody Test and PCR Test

Testing can be useful for more than simply determining whether someone is carrying a virus. Once a virus is recognized, it is equally important to measure its severity, which in turn determines the patient’s need for hospitalization. Testing can be categorized as diagnostic tests and antibody tests. Diagnostic tests can be further divided into molecular tests and antigen tests. So, PCR tests come into the category of molecular test that detects the genetic material of the virus. Antibody tests are a detection mechanism for detecting antibodies in the bloodstream.

What is Antibody Test?

Antibodies are nothing but proteins known as gamma globulin proteins, or commonly referred to as immunoglobulins. Antibodies are present in the blood stream and other body fluids of vertebrates. They help the immune system of the vertebrates identify and eliminate foreign particles. So, an antibody test looks for the presence of antibodies in the bloodstream. Typically, the human body produces antibodies in the natural manner for its own defense, but there are also many procedures to stimulate their production via immunization. An antibody test screens for antibodies in the blood in order to determine if an individual has been infected with a virus or pathogen in the past. The test does not determine if that person is currently infected but if he or she had any past infection. For example, in case of COVID-19, a positive antibody test result confirms that the individual has been infected with SARS-CoV-2 before.

What is PCR Test?

A polymerase chain reaction (or PCR) is a molecular test and a valuable tool for monitoring gene expression, quantifying food pathogens, testing viral load, and clinical diagnosis. It is an in-vitro method for the enzymatic synthesis of specific DNA sequences using a lab technique called PCR. The method involves amplifying any region of a DNA by repeated cycles of duplication caused by an enzyme called DNA polymerase, which occurs in the cells of living organisms. The polymerase works by binding to a single DNA strand, followed by generating the complementary strand. The method was originally developed by Kary Mullis in 1983 and since then, it has contributed greatly to the progress of studies one the genomic structure of various organisms. The test requires a fluid sample collected from nasal or throat swab and then it looks for the genetic material of the virus. It is a diagnosis test for detecting early infections before antibodies have been developed.

Difference between Antibody Test and PCR Test

Significance

 – Both antibody test and PCR test are the two most frequently used methods for the diagnosis of a possible viral infection. Even in the wake of the current coronavirus pandemic, the two techniques have proved to be the two dominant methods for testing people for COVID-19. Antibodies basically help the immune system identify and eliminate foreign particles. So, an antibody test looks for the presence of antibodies in the bloodstream. A polymerase chain reaction (or PCR) is a diagnosis test that directly detects the presence of antigens, rather than the presence of antibodies or immune response of the body.

Test

 – An antibody test determines if an individual had any past infection. It does not determine if a person is currently infected because the body typically starts producing antibodies a few days after the infection, but not before. A PCR test, on the other hand, is a diagnosis test for detecting early infections before antibodies have been developed. It is an in-vitro method for the enzymatic synthesis of specific DNA sequences using a lab technique called PCR. It basically amplifies a particular segment of a targeted DNA by making millions or billions copies of it and then looks at the genetic information of the virus if present.

Procedure 

– An antibody test screens for antibodies in the blood in order to determine if an individual has been infected with a virus or pathogen in the past. It detects the virus indirectly by analyzing the body’s immune response against the virus. A PCR test involves amplifying any region of a DNA by repeated cycles of duplication caused by an enzyme called DNA polymerase. The test requires a fluid sample collected from nasal or throat swab and then it looks for the genetic material of the virus. PCR test gives a clear picture of who is infected with the virus so that he or she can be put into isolation to curb the further spread of the virus.

Antibody Test vs. PCR Test: Comparison Chart

Summary

While both antibody tests and PCR tests are the two most frequently used methods for the diagnosis of a possible viral infection, they have their caveats. An antibody test, as the name suggests, looks for the presence of antibodies in your blood which only determines if you have been infected with some virus at some point of time in the past, but does not determine the state of current infection. A PCR test is a diagnosis test that detects an active infection by analyzing the presence of antigens, rather than the presence of antibodies. A PCR test is more reliable because they are accurate and it gives a clear picture of a person’s clinical status very early on. However, PCR tests are generally expensive to conduct because they require specialized equipment and skilled professionals to perform the test.

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