Every day nearly a hundred thousand people are found COVID-19 positive. Every country is trying to test the maximum number of people to ensure proper treatment for those who are infected by the deadly virus. A person who has tested positive for COVID-19 is either hospitalized or isolated, depending on the severity of the symptoms. At the same time, people whose test results return negative continue on with their everyday life. But what does a negative COVID-19 result mean?
We all have heard the news of famous people testing positive for COVID-19. The President of the United States, Donald Trump, was one of those famous people whose COVID-19 tests showed a positive result. After getting the best possible treatment for over a couple of weeks, the President of the United States is healthy again. Experts say that the news that the President is no longer suffering from COVID-19. The comment is not based on the test results but on the absence of symptoms of COVID-19.
The test shows that you are infected with COVID-19, but we currently don't have any test that confirms that the virus no longer exists in the body of the infected person. As a result, a person who is deemed to be healthy based on a negative COVID-19 test could still infect other people.
At the moment, the White House is relying solely on these COVID-19 tests to ensure that everyone is fit and fine. These are the best possible tests that we have got at the moment, and they are not 100 percent reliable.
But why these tests are not completely reliable? The answer is that each test checks for a particular enzyme of the COVID-19 virus. A negative on one or two such tests do not confirm that a person is not infected. As a result, there is no clear way to say that a person who tested negative for COVID-19 in a certain test is healthy. Each test is looking at a certain aspect related to the COVID-19 virus.
Many countries are coming up with tests that provide a result within hours instead of days. One such test called BinaxNow showed a negative result when used on Donald Trump. He underwent a more complicated PCR test, which showed that the COVID-19 virus is still present in his body in a minute amount. The reliability of these tests is a significant issue. When we talk about any such tests, we talk about a false positive. A false positive means a person who is healthy is declared infected by the result. This result might cause some issues, but a couple of more reliable results would declare that they are healthy.
However, a person can also get a false negative in a test result. In such a situation, the person is highly unlikely to appear for a second test or a more reliable test. In the end, this person might infect others at their home or workplace. In the US, the FDA has accepted most PCR and antigen tests. However, tests involving a viral culture and probes for subgenomic RNA are yet to become a part of the standard test kits. The US President, Donald Trump, underwent one such experimental test. Thus, PCR and antigen tests are the most common testing method at the moment.
The PCR test is more reliable as it is a molecular test. What it means is that the test seeks genetic material that is exclusive to the COVID-19 virus. These tests also use an amplification process, which allows the genetic material to multiply rapidly for easy detection. As a result, even a tiny amount of virus present in a person shows up on the test. Some advanced PCR tests can also help determine how long the virus has been inside a person's body. These tests involve a cycle threshold (CT), which increases as the number of viruses declines.
The PCR test is highly reliable, but it takes some time to yield the results. As a result, most people would first undergo a simple antigen test. The BinaxNOW test, which Mr. Trump underwent, is one such test. These tests look for proteins or antigens that are made by a coronavirus.
Tests such as the PCR involve the amplification step that allows easy detection of even a small amount of virus present in the body. However, it takes some time for the culture to grow to a detectable level. As a result, antigen tests don't involve this step. So, a person who has a significant amount of virus in the body at the time of testing would get a positive result in an antigen test. On the other hand, a person who has been recently infected by the virus might not have a detectable amount of proteins and antigens in their body.
As a result, the antigen result of that person might come negative. Additionally, if the person has no sign of illness, he or she would probably consider themself fit and won't take any subsequent test. The unreliability of the antigen tests has led the FDA to issue an emergency clearance to tests such as BinaxNow. These tests need to be used within seven days of a person showing symptoms of COVID-19. The researchers are not sure how accurate the test will be after this seven-day window.
So, if PCR tests are highly reliable, but do they have any limitations? As a matter of fact, all these tests have a significant limitation. These tests look for the presence of the virus and not its state. As a result, you cannot say if the virus is dead or alive. So, a person who has been infected by COVID-19 and is now healthy would still have dead viruses in their body. As a result, the PCR test might come positive.
Researchers have come up with a possible solution to this problem, virus culture. This method works by taking a sample from a person's airway and using the virus to infect cells in a lab. This procedure is not available for public use as the steps are complicated and require a high-containment facility. Furthermore, you need researchers who are certified to work with such infectious pathogens.
To circumvent this issue, scientists are developing a new system that allows PCR tests to look for subgenomic RNA to help detect the virus. Subgenomic RNA is a type of genetic material that is produced as the virus takes over a healthy cell in our body. This process allows us to confirm the presence of a virus quickly and safely, without any need to grow a culture in the labs.
Health reports for Mr. Trump indicated that he went through this subgenomic RNA test, and no virus was found in his body. Researchers are trying to perform this test with cultures outside the body but haven't made any significant progress so far. Culturing a virus doesn't mean that it is transmissible. At the same time, a highly contagious virus isn't always culturable.
As of now, the FDA has not approved virus culture or subgenomic RNA tests for public use. Researchers working on these tests might not follow the same process, so the results are not concrete. So, the best option for us is to follow the guidelines issued to prevent the spread of the COVID-19.
In case someone you know is infected, take special care when around them. If you or anyone around you shows symptoms of COVID-19, get tested. A test and early detection wouldn't hurt anyone.
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