Test FAQs

COVID-19 Test Frequently Asked Questions

COVID-19 tests are used to detect whether the patient is currently or previously infected with the SARS-CoV-2 virus by methods such as PCR tests, antibody tests, antigen tests, and chest CT tomography.

COVID-19 Antigen Tests

1. What is COVID-19 Antigen?

An antigen is a molecule or molecular structure outside of a pathogen that, when detected in the human body, can trigger an immune response. Common antigens include simple intermediate metabolites such as carbohydrates, fats, hormones, and larger molecules including polysaccharides, phospholipids, nucleic acids, and proteins.

2. How does COVID-19 Antigen Tests work?

Antigens are present on SARS-CoV-2 viruses, which can be often be found in the respiratory tract during early stage infections. These antigens, when detected, serve as markers for disease exposure.

3. When should COVID-19 Antigen Tests be used?

As the SARS-CoV-2 virus multiplies, the levels of the virus rise, peak around 1 week, then fall off around 2 weeks. COVID-19 antigen tests can be used around 2-14 days after infection to detect the presence of COVID-19 antigens.

4. How accurate are COVID-19 Antigen Tests?

The accuracy of COVID-19 antigen tests are slightly lower than the gold standard PCR tests, however, its accuracy can reach 90% or above. The clinical specificity and sensitivity of the INDICAID COVID-19 Rapid Antigen Test reaches up to 99% and 96% respectively.

5. Who should use COVID-19 Antigen Tests?

COVID-19 antigen tests are fast, easy-to-use, affordable, and is suitable for home or clinical use. These tests can be used for high-risk populations, or those to frequent high-risk environments as a tool for wide-scale population screening. Regular testing once per week is recommended.

COVID-19 Antibody Tests

1. What are COVID-19 Antibodies?

As your body starts to fight off infection, the immune system is triggered by the presence of the antigens and begins to produce antibodies to counteract the virus. Antibodies that fight the SARS-CoV-2 virus includes immunoglobulin M (IgM), which is produced 5-7 days after infection, and immunoglobulin G (IgG), with is produced 10-15 days after infection.

2. How does COVID-19 Antibody Tests Work?

The immune system begins to produce antibodies around 7 days after infection. Through detecting the presence of SARS-CoV-2-specific antibodies, the COVID-19 antibody test can determine the status of infection.

COVID-19 antibody tests are used on blood or plasma samples, as antibodies are commonly found.

COVID-19 PCR Tests

1. How does COVID-19 PCR Tests Work?

PCR tests are molecular diagnostic tests that amplifies and detects the presence of SARS-CoV-2 nucleic acids in patient samples to determine the status of infection.

2. Who should use COVID-19 PCR Tests?

COVID-19 PCR Tests are suitable for patients who need a diagnosis for COVID-19 infection. These tests are carried out by professionals in a medical institution or testing center.

3. How accurate are COVID-19 PCR Tests?

COVID-19 PCT Tests are highly accurate and is the gold standard for disease diagnosis.

4. When should COVID-19 PCR Tests be used?

COVID-19 PCR Tests can be carried out after infection.

PHASE Scientific has launched a full range of COVID-19 PCR Testing products, including sample collection, viral RNA extraction, and PCR detection kits. Clinical verification shows the detection accuracy and specificity of PHASE Scientific’s products is higher than other industry leading products.

Should I use COVID-19 PCR Tests if I have already used the COVID-19 Antigen Test?

COVID-19 PCR Tests are needed if the COVID-19 antigen test indicates a positive result.

If the COVID-19 antigen test indicates a negative result, but the patient has been recently exposed to a high-risk environment or population, it is recommended to conduct a COVID-19 PCR test to confirm the status of infection.

The Difference between PCR, Antigen, and Antibody Tests

	PCR Tests	Antigen Tests	Antibody Tests
Concept	SARS-CoV-2 has genetic material in the form of RNA. Presence of COVID-19 specific viral RNA from patient samples indicate that the patient is SARS-CoV-2 infected.	Antigens are present on the surface of the virus. Presence of COVID-19-specific antigen in patient samples indicate that the patient is SARS-CoV-2 infected.	Production of antibodies are triggered after COVID-19 infection. Status of infection can be confirmed by detecting the presence of IgM or IgG antibodies in patient blood samples.
Testing Principle	PCR tests amplify and detect targeted region of SARS-CoV-2 genetic material.	Antigen tests detect SARS-CoV-2 antigen in patient samples.	Antibody tests detect IgM and IgG antibodies targeting SARS-CoV-2 in patient samples.
Sample Type	Nasal, nasopharyngeal swab, oropharyngeal swab, deep throat saliva	Nasal, nasopharyngeal swab, oropharyngeal swab	Blood (Whole blood, plasma, serum)
Biomarker	SARS-CoV-2 virus	SARS-CoV-2 antigen	SARS-CoV-2 IgM and IgG antibodies
Suitable period for use	From onset of infection	From 2 days after infection	From 7 days after infection
Operation Time	4-6 hours	Around 20 minutes	Around 20 minutes
Operation Requirements	Professional medical operator and lab equipment	No professional operator or equipment required	No professional operator or equipment required

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