Which tests are being used for diagnosis of COVID-19??

COVID-19 Diagnostic Tests and Their Types

As we all know that the whole world is suffering from COVID-19. More than 8 million people are its patients and about half million died from this dangerous disease. First step in the treatment of any disease is its diagnosis and same is the case with COVID-19. A variety of tests are being performed around the world to diagnose corona virus. The methods of these tests differ from each other, as well as the sensitivity of their results.

PCR test or Swab test

This test is used to diagnose people who are currently ill with Covid 19. This is what we have been hearing about.

Principle of Working

This test is performed with a sample of mucus that is usually taken from a person's nose or throat. This test can also work on saliva. It searches for the genetic material of the corona virus. The test uses a technology called PCR (Polymerise Chain Reaction), which greatly enhances the presence of viral genetic material. This content can be detected when a person is actively affected.

There are two main parts to this test. First, RNA (ie ribonucleic acid) is extracted from the sample of the person concerned and then the isolated RNA is examined. In the second stage, the presence of the virus in the RNA is tested. The virus is compared to a sample of an infected person with a 'non-control' sample, which means the genetic sequence of the virus that identifies the corona virus. If the virus is found in the sample, the person's results are positive.

Reliability or Accuracy

In general, these are the most reliable tests. However, a few days may pass before the virus begins to film in the throat and nose, so this test will not identify the person who has recently had an infection. And swabs can sometimes fail to pick up signs of an active infection.

Result Timing

These samples are usually sent to central labs for analysis, so it may take several days for the results to return. The wait - in our estimation, many hours - has been a long time coming. There are also two rapid tests of PCR, which can be run on special devices which are widely distributed in the United States, the fastest by Abbott Laboratories, can deliver results in 13 minutes, but one Studies show that this test can have a chance of error more than 10%.

Antibody test

 

Antibody tests identify people who have previously been infected with the corona virus. They do not show if anyone is currently infected. This is a great way to track the spread of Corona virus primarily through the population.

Principle of Working

This is a blood test. It looks for antibodies to the corona virus. Our body makes antibodies in response to infectious agents such as viruses. These antibodies are usually produced more than four days to a week after infection, so they are not used to diagnose existing disease.

Reliability or Accuracy

There are more than 120 antibody tests in the market. In general, these tests are not reliable enough to work on the results of individuals. And researchers say that even if you believe you have antibodies to the corona virus, it is not known if it will prevent you from getting sick again. Although, these tests can provide good information about infection rates in a society where errors in individual outcomes have little effect.

This test is very useful for large-scale screening as it will differentiate those who do not show symptoms. On the other hand, those who have recovered without showing any symptoms can take plasma for the treatment of severely affected patients with corona.

Result Timing

These tests usually produce results within a few minutes based on a drop of blood taken from a finger. Some research labs use a more sophisticated antibody test, called ELISA (enzyme-linked immunosuppression), which is more accurate but not widely available.

Antigen test

This test identifies people who are currently infected with the corona virus. It can be used as a quick test to detect active infection. Initially it will not be used to diagnose the disease, but it can be used to test people who need more examinations.

Principle of Working

Antigen tests can detect the virus in the secretions of the nose and throat. It does this by searching for proteins from viruses (opposite to diagnostic tests, which look for genetic material). This is the same technology used for rapid strip testing in doctor's office.

Accuracy or Reliability

The first of these tests received FDA clearance on May 8 in America. The company, Quiddle Corporation, says it will use the first 40,000 tests to get a better idea of ​​the accuracy of its tests. Researchers do not expect this to be as accurate as the PCR diagnostic test, but it is possible that the antigen test could be used to screen patients for infection. Dr. Jordan Laser, Lab Director of Northern Health, notes that antigen testing is used for rapid stripe tests, which are reliable, and rapid flow tests, which are not.

Result Timing

These tests should provide results in just a few minutes. As a result, they can be used to screen people in hospitals, certain workplaces, or other places where it is important to find out immediately if someone is currently at risk of contracting the disease. But unless these tests prove to be very accurate, doctors will still need to adopt a positive result with a PCR test for a medical diagnosis.

Conclusion

In Pakistan government hospitals are using only PCR or Swab test and its totally free while private laboratories are charging about Rs.8000 for it.

Antibody test is not used by government hospitals in Pakistan while  private labs.are charging about Rs.2000 for this test.

Antigen test is not being used in Pakistan by government or private sector.