Because of Coronavirus 19, PCR or Rapid diagnostic tests are being conducted in many countries. Here we compare PCR Diagnostic Tests with Rapid Diagnostic Test. First of all Diagnostic tests are largely classified into In vivo Diagnostics and In vitro Diagnostics.

In vivo Diagnostics : To analyze one's health status inside of the human body.

Ex) X-ray, CT Scan, MRI Scan


In vitro Diagnostics : To analyze specimens derived from the body such as Blood, Urine to identify infection by foreign object

Ex) Rapid Kit, PCR Kit


<What is PCR Diagnostic Test?>

PCR(Polymerase Chain Reaction) is a test method in molecular scale that corrects RNA from a specimen such as saliva or sputum from a suspected patient and compares it with the RNA of a real patient to determine positive if it matches a certain ratio or more. So, it is also known as Molecular diagnostics. PCR is a test method currently used in almost all processes of experimentation by manipulating genetic material, and is a method of amplifying a specific target genetic material to be detected. Since genetic material with the same nucleotide sequence can be amplified in large amount, it is used to amplify human DNA to diagnose various types of genetic diseases. In addition, it can be applied to DNA of bacteria, viruses, and fungi and used for diagnosis of infectious diseases.

<Process of PCR diagnostic test>

Process of Molecular Diagnostic test is like the below

1) Collecting sample from Blood, Urine, Excrement, Cerebrovascular fluid, etc.

2) Extracting DNA / RNA from the sample

3) Putting it into Reagent

4) Amplifying DNA/RNA by Conventional PCR or RT PCR

5) Reading the result on Screen 

<What is Rapid Diagnostic Test?>

Rapid Diagnostic Test is the analysis of a patient's sample (usually blood) to check for the presence of certain antibodies(qualitative tests) or to determine the amount of antibodies present (quantitative tests). Rapid Diagnostic Test is also called, Immunoassay diagnostics.

There are five types of immunoglobulins (lgM, lgG, lgE, lgA, and lgD). The three most common measurements are lgM, lgG, and lgE. lgM and lgG antibodies work together to create short- and long-term immunity against infection. lgE antibodies are primarily associated with allergies. Also, a detection of lgM antibodies tended to indicate recently exposure to the initial antigen, while detection of whole or lgG antibodies indicates exposure to the antigen long time ago. 

<Process of Rapid (Immunoassay) Diagnostic Test>

1) Collecting Sample from Blood or specimen from body fluids or secretions

2) Adding sample to the kit

3) Dropping sample buffer on the place the sample was dropped

4) Read the result on the kit

<Pros and Cons of PCR and Rapid diagnostic test>

1) Advantages of PCR Diagnostic Test : 

A. Accuracy more than 95%

B. Able to diagnose before antibody is formed in the body on the initial stage of infection (within 7days)

2) Disadvantages of PCR Diagnostic Test :

A. an expert is required even only for collecting specimen

B. an expert is required for performing PCR and analysis

C. 4~6 hour is needed for obtaining the result of the test.

D. Relatively expensive price of test

3) Advantages of Rapid diagnostic test : 

A. only 20mins is needed for the test.

B. Self diagnosis is possible

C. Relatively low price of test

D. Able to detect initial antibody(around 7days from infection) or formed antibody(after 14days from infection)

4) Disadvantages of Rapid diagnostic test :

A. Its accuracy is 70%~80%. (it is very large number for misdiagnosis)

B. not possible to diagnose before 7 days from infection