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Methods and strategies for diagnosis: What you should learn

by the owl speaks

Early disease diagnosis plays a vital role in preventing a pandemic. Continuous efforts are being made by researchers around the world to develop a COVID-19 diagnostic method that is easy and accurate to monitor spread. Take a look at a few current COVID-19 diagnostic approaches.

1. Nucleic Acid Amplification Tests (NAAT)

It is known to be the key research tool for COVID-19 diagnosis. NAAT is used by reverse transcription-polymerase chain reaction (RT-PCR) to genetically detect and amplify a special sequence of the COVID-19 RNA. [1] The procedure is carried out mainly during the acute period of the disease. RT-PCR test is precise and highly sensitive. It detects viral load even though it is low in number and avoids false-negative outcomes. The quality of the study is also fairly optimum. The negative aspects of the PCR test are time, and additional parameters are needed.

2. Viral Sequencing

The RT-PCR viral sequencing test is useful in detecting sequences of COVID-19 viruses. It only targets the retained portion of the pathogen genome, however. Consequently, as we know, pathogens tend to mutate, the chances of false-negative tests during the PCR test are greater. Viral sequencing is a technique of next-generation sequencing (NGS) that involves metagenomics, NGS based on amplicons, and NGS based on hybrid captures. It is highly sensitive to the PCR process, which can be used to detect secondary or double-check false-negative RT-PCR samples. The only negative side of this solution is its high expense.

3. Serological tests

The test is used to determine the body’s immune response when it comes across a particular virus. Where the first outbreak began, the human body was unable to produce its antibodies as new to humanity. In the early days, this had limited the diagnosis. Henceforth, this method of treatment is commonly used by health care practitioners to treat contaminated cases. They do so by a procedure called convalescent plasma, in which the patient’s given blood samples are collected (with donor permission) and distributed to patients who are seriously ill or have reduced chances of recovery. Serological testing is a form of passive antibody therapy that is primarily used to help positive patients with COVID-19 develop immunity against the virus. The FDA approves the check. The negative aspect of the test is the presence of allergens or substances which interfere in the donor’s blood. When the NAAT test comes negative the procedure can be used.

4. Rapid Antigen Testing

The test is known for fast and low-cost detection. There are several types of rapid antigen tests but, among them, immunochromatographic fluorescence is reliable, quick, and simple. This helps track the outer protein layer of the virus in the nasopharyngeal swab and urine sample that includes genetic material. Except for MERS, the rapid antigen test has low specificity in coronavirus detection. Considering that most COVID-19 patients are not detected during the infection’s incubation phase, this approach does not serve as the best COVID-19 diagnostic tool.

5. Computer tomography

It is a non-invasive method performed by taking several cross-sectional chest images of a human. Then, radiologists examine the images to find any irregularities in the lungs. The magnitude of COVID-19 is determined based on the results from the CT scan. If it is only two days after the onset of symptoms, the CT results should be normal while the highest involvement in the lung can be seen after 10 days. Similar to RT-PCR, the CT scan has an 86 to 98 per cent higher sensitivity and less false-negative rates.


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