THE DIFFERENCE BETWEEN COVID-19 TESTING TYPES
What is the difference between COVID-19 testing types? The coronavirus disease 2019 (COVID-19) originated from Wuhan, China, in late December 2019 and just after a few days, a person returned to the United States on 20 January 2020, suffering from fever, vomiting, nausea, and coughing. The man was admitted to the emergency care clinic and the next day the Centre for Disease Control (CDC) after testing declared him positive for COVID-19. In New York on March 2nd, 2019 the first case of COVID-19 was confirmed in a non-travel individual.
The World Health Organization stated, “Test, test, test” is the only measure to control the viral spread and lessening the clinical manifestation. But globally, the lack of proper and adequate testing and confusion in interpretation are the main issues for healthcare professionals. Antigen testing, antibody testing, polymerase chain reaction (PCR) testing procedures were applied to diagnose the virus by taking samples from suspected individual’s body fluids, mainly through nasal swabs.
Testing is an important component to detect disease and control across the globe. The RT-PCR test is the “gold standard” test that detects the presence of the virus in humans, but COVID-19 pandemic strategies have been changed and chiefly RT-PCR based testing was performed, although, antibody and rapid antigen detection diagnostic tests (Ag-RDT) were available for diagnosis. Worldwide authorities included antigen testing in treatment strategies for the mapping of disease.
SWAB TESTING BY PCR
The virus was at its peak after the first seven days and symptoms appeared. Swab samples were taken from the nasopharyngeal region as they give more accurate results during PCR testing. The standard PCR test diagnoses and detect viral RNA reverse transcription-PCR. At the start of pandemic testing done in regional laboratories and it will take time almost two days but novel systems help in detecting virus within one day while antigen testing devices are available too but false-positive results were seen due to poor sensitivity.
Antibody testing is used to diagnose individuals by taking blood samples to check for any past COVID-19 infection. Results were received the same day but its effectiveness is not as accurate as PCR testing. After covid-19 infection body develop antibodies (IgG and IgM) and was detected by ELISA tests and the result were seen in just 20 minutes. Antibody testing is limited due to poor specificity and chances of false results.
The Ag-RDT test is used for the diagnosis of respiratory pathogens, including respiratory and influenza viruses, and nowadays it is extensively used to diagnose SARS-CoV2. Antigen test has advantages over RT-PCR, one of the main advantages is cost and results in timing. RT-PCR take almost six to eight hour but antigen test just take roughly 15 minutes and antigen test takes 20 minutes but it is least effective. The antigen COVID-19 test is a lateral flow, rapid test that utilizes a liquid sample for detecting SARS-CoV-2 virus protein fragments.
COMPARISON OF TESTING FOR COVID-19
|Antigen test||RT-PCR||Antibody Test|
|Target viral antigen||Target viral RNA||Target antibodies for past infection|
|Nasopharyngeal Swab is required for diagnosis||Oral and Nasopharyngeal Swab are required for diagnosis||Blood|
|Moderate sensitivity and False Negative results||High sensitivity||Less sensitivity and False-positive results|
|Easy to use||Complex||Easy to use|
|Performed outside the lab and no need of well-established labs||Sophisticated laboratory equipment is required for testing||No need for sophisticated labs|
|Return results within 15 minutes||Return results within 6-8 hours||Return results within 20 minutes|