COVID-19 testing is essential to accurately identifying who has been infected with COVID-19 and to containing the spread of this disease. The main types of COVID-19 tests work in different ways to diagnose infection or assess immunity.
Serology tests can detect antibodies against the causative agent of COVID-19 weeks or months after the first exposure to the virus. Polymerase chain reaction (PCR) and antigen tests identify the genetic materials and surface protein, diagnosing current virus infections.
In this article, we will examine some of the testing options available. Then, we will answer the following question: what to do in case of a positive COVID-19 test result?
Real-Time Reverse PCR Tests
The Real-Time Reverse PCR Test is performed to detect the virus’s genetic material in an individual’s upper respiratory tract and diagnose active COVID-19 infection. A positive result signals the presence of viral nucleic acid in the sample and is indicative of active infection with2019-nCoV.
How Does the RT-qPCR Test Work?
The Real-time reverse transcription polymerase chain reaction (RT-qPCR) test can be run either in a singleplex or multiplexed format in a single response and amplification setup. The test uses primers and probes to detect specific regions in the coronavirus nucleocapsid gene.
For the identification of an RNA virus as COVID-19, the RNA extracted from the sample should be first reverse and transcribed to cDNA. Subsequently amplified through a polymerase chain reaction. The amplified DNA generates a fluorescent signal, the intensity of which is monitored to detect the presence of Coronavirus, which is considered as COVID-19 positive test result.
In a research published in July 2020 by the US National Library of Medicine, the accuracy of the RT-qPCR test was identified as 97.2%. To this day, RT-PCR is still considered a gold standard in the diagnosis of COVID-19. The minimum turnaround time of the PCR COVID-19 test is about 24 hours.
Antigen tests for COVID-19 search for the pieces of proteins that compose the COVID-19 virus to determine if the person has an active infection or not.
How Does the Antigen Test Work?
During the rapid antigen test, Coronavirus antigens in the nasal swab specimen react with the antibody-coated nanoparticles present in the reactive testing strip. This type of COVID-19 test is a rapid lateral flow immunoassay test.
Antigen tests are more accurate when used during the first week of infection, with an accuracy rate of 72%. The turnaround time of the coronavirus rapid antigen tests is as fast as 13-15 minutes.
In the scenario where the COVID-19 antigen test result is positive, the individual is likely infected with the COVID-19 virus. The exact sensitivity depends on the type of test and the manufacturer.
The Primary Response of Symptomatic and Asymptomatic Covid-19 Patients
The response of symptomatic individuals with a positive RT-PCR COVID-19 test result should abide by the following protocols:
- Avoid public transport and gatherings
- Call a doctor for medical advice
- Immediate reporting to local health authorities in case of a worsening of symptoms.
It is also necessary to prepare a list of people with whom the individual has had contact in the two days before the onset of symptoms. This list will be useful to the Prevention Department for the tracing of close contacts.
Asymptomatic individuals with COVID-19 positive test results should adopt the following precautions:
- Quarantine and isolation
- Using a separate bathroom and household items
- Maintaining distance from family members
- If they remain asymptomatic for ten days of quarantine, then they can return to their routine activities.
Why May False Positives Occur?
There are several reasons behind a false RT-PCR positive test result, including:
- Laboratory errors
- Clerical errors
- Testing the wrong sample
- Contaminated reagent used
- Inappropriate handling
- Use of the wrong procedure
Similar to RT-PCR, antigen tests may also turn out to be false positive. Some of the reasons are shared with RT-PCR tests, including:
- Sampling miss handling
- Sample contamination
- Sample inappropriate storage
- Cross reaction with other antigens
- External factors such as high concentration of nasal spray or other chemical substances
Individuals with COVID-19 positive results should isolate themselves immediately to avoid spreading the infection to other people. Unconfirmed infected individuals should quarantine themselves, keep monitoring their symptoms, and get tested.
COVID-19 positive test holders can consult their local health department and healthcare provider to receive more detailed instructions on checking their symptoms and reporting information.
Since its foundation in 1992, Wondfo Biotech has been one of the leading healthcare providers of reliable POCT solutions. The company has taken concrete actions to fight the COVID-19 pandemic. Wondfo offers a wide portfolio of COVID-19 testing, ranging from RT-PCR tests and antigen tests to antibody tests.
Wondfo strictly complies with international regulations and standards, including CE certificates, FDA certificates, FSC certificates, ISO 9001:2008, and ISO 13485:2012 quality system certifications.
Currently, Wondfo’s POCT solutions are available in more than 140 countries worldwide. Click here to discover Wondfo’s complete COVID-19 diagnostic solutions.