Covid-19 Test Types

Stay up to date with all the different types of Covid-19 tests that are currently live and in-use. Please be advised that you should independently research the entry requirements for your particular destination, as these can change both frequently and spontaneously.

PCR

Polymerase Chain Reaction

About
This is the most commonly used test for COVID-19. Antigens are particles produced by disease-causing organisms that insight an immune reaction in the human body. PCR tests are used to detect antigens rather than antibodies or the body’s immune response.

What does the test find?
PCR tests can help identify the presence of the virus in a person before the symptoms of the disease are detected.

Sample
Samples can be taken with a nasopharyngeal swab, a nasal swab or through saliva. The sample undergoes reactions and amplification to accurately detect the virus.

Specificity & Sensitivity
Specificity- the chance of detecting the virus is 80-85 %.

RT-PCR

Real-Time Polymerase Chain Reaction

About
This is the most commonly used test for COVID-19. The process of this test is similar to that of PCR.

What does the test find?
The test is conducted by taking a swab from the patient’s nose or throat. Since one swab does not contain adequate amounts of RNA, to test more work is done on the sample to make it possible to test. The sample undergoes reactions and amplification to accurately detect the virus.

After the procedure, the confirmation of the presence of the virus is done by the fluorescent (color) signal of the sample.

Sample
A swab from the patient’s nose and/or mouth is taken for the testing process.

Specificity & Sensitivity
The specificity and sensitivity of the real-time PCR test is not 100 percent but it does help in detecting the virus early on.

Antigen

Antigen

About
Antigen tests are used for the detection of a specific protein present in the virus that evokes the body’s immune response.

What does the test find?
Spike protein is present in coronavirus which eases its entry into the cells of the human body. The nasal swab taken from the patient is immersed in a deactivating solution for the virus. The solution is then put on a test strip and if the individual is infected lines appear on the test strip within 15 mins.

Sample
A sample is taken in the form of a nasal swab.

Specificity & Sensitivity
Due to the lack of antigen material in the sample, it is possible to get false negatives so RT-PCR needs to be done for confirmation.

Antibody

Immunoglobulin G

About
Antibodies are produced in your body naturally by your immune system to help you fight off infections. Antibody tests are also called serological tests and can tell you if an individual was recently exposed to the virus and whether they have antibodies against the virus.

What does the test find?
A few drops of blood are collected and then are placed on a cassette or cartridge that contains proteins from SARS-CoV-2. The positive result is indicated in the form of lines.

Sample
A few drops of blood are needed as a sample.

Specificity & Sensitivity
The sensitivity of a test is its ability to detect the presence of antibodies against the virus in blood samples with a positive NAAT. Specificity is the reliability that a test only detects SARS-CoV-2 and is not positive for any other virus.

LAMP

Loop-mediated Isothermal Amplification

About
The procedure of the LAMP test is similar to that of PCR but instead of using various temperatures like PCR, LAMP uses a constant temperature.

What does the test find?
The swabs from your nose and throat are used to convert the viral RNA sample to DNA and then multiple copies are made using LAMP technology and with the use of chemical reagents and fluorescent dyes, if the sample is positive, the result is a cloudy mixture.

Sample
Samples are collected in the form of the throat or nasal swabs. Another way is using coughed up mucus as a sample.

Specificity & Sensitivity
Similar to RT-PCR and PCR, the LAMP results are also highly sensitive. LAMP can only detect if the individual has the virus at present it can not detect if someone has recovered from the virus or if the virus is active or not.

NAA

Nucleic Acid Amplification

About
The Nucleic Acid Amplification test is a molecular test the can detect the genetic material of the virus from the sample collected from the patient.

What does the test find?
The nucleic acid amplification test first examines the RNA from the upper respiratory tract for an initial COVID-19 diagnosis.

Sample
Samples are collected from nasal swabs and throat swabs.

Specificity & Sensitivity
In light of the data present, it is observed that NAAT test results are highly accurate and a positive or negative result from an NAA test is likely to be true.

TMA

Transcription-Mediated Amplification

About
TMA uses technology that can amplify specific regions of DNA or RNA better than RT-PCR.

What does the test find?
Transcription-mediated amplification is used to bring the RNA to a high level. Since the SARS-CoV-2 gene has an RNA based nature, the rate of mutation is expected to be high. Most of the examination is done by targeting two different places to avoid missing the virus due to a mutation in the primer binding site.

Sample
Nasal or throat swabs are used as samples.

Specificity & Sensitivity
TMA tests are very sensitive during the first week of the infection.

AMP-PRB

Amplified Probe

About
Microbiology tests that are used to check the presence of an infectious agent are done through an amplified probe technique.

What does the test find?
The nucleic acid from the swab sample is isolated to eliminate substances that hinder the amplification process. A specific set of primers is used to determine the COVID-19 sequence.

Sample
Nasal swabs are used as samples.

Specificity & Sensitivity
It is an uncommonly used testing modality and so the sensitivity and specificity remains undetermined.