COVID-19 is still raging after 11 months and testing has only been the most effective way to keep in check the rate of increase in the active cases. With time and the increasing need, different types of COVID -19 tests are developed and are used. But the number of tests has also birthed confusion in people about which tests to take?
So, what are the best COVID-19 tests?
Amongst the many types of COVID-19 tests available around, it becomes quite important to know the details of these tests. Because all these covid tests have their advantage and usage and also they differ according to the conditions in which they give the best results.
COVID-19 tests are broadly classified into two groups
Diagnostic tests and Antibody tests
1. Diagnostic tests – Test to diagnose current infection in the body
Diagnostic tests are of 2 kinds—Molecular test, Antigen Test
Molecular tests are used to find the current infection. Popularly known as the PCR test, nucleic acid test, molecular test, a viral test is used to find if someone is currently infected by the COVID-19 virus.
How the sample is taken– Samples are taken from nasal swabs, saliva, throat, or other fluids of the body.
How does it work? – Test looks for the genetic material in the sample which only comes from the COVID-19 virus. PCR technology is used to amplify and identify genetic material.
How accurate is the molecular test – The test is one of the most accurate but the genetic material starts accumulating in the passages after some time so a very recent infection might not be detected. A nasal swap sample is better to get an accurate result.
Chances of getting a false negative can be from 2% to a maximum of 37% and that of getting a false positive (report says positive but you actually are not infected) is close to zero.
It can take from a day up to a week for the result to come.
In a pooled testing several samples are combined and are run under a molecular test. In case of a negative result, all the individuals are negative whereas in case of a positive result all the individuals need a second test. This is a fast way to get more people tested.
Antigen tests are also diagnostic tests and also are performed on a nasal, throat, or saliva swab but instead of looking for genetic material, it looks for protein fragments of the virus.
The reported rate of false-negative results is as high as 50%, which is why antigen tests are not favored by the FDA as a single test for active infection. However, the FDA recently provided emergency use authorization for a more accurate antigen test. Because antigen testing is quicker, less expensive, and requires less complex technology to perform than molecular testing, some experts recommend repeated antigen testing as a reasonable strategy. According to one test manufacturer, the false positive rate of antigen testing is near zero. So, the recent experience of Ohio Governor Mike DeWine, who apparently had a false-positive result from an antigen test, is rare.
Antigen tests have higher chances of giving a false negative which accounts for about 50%. Although this test is not favored by the FDA but is still authorized to be used under required circumstances. Because the antigen test is less expensive and gives the results faster. Also, the antigen test doesn’t require any complex technology as compared to the molecular test. That is the reason, the antigen test is done more than once to confirm the reason for illness.
Although in the antigen test, the false positive rate is near to Zero.
This antigen test gives the fastest result in a few minutes.
2. Antibody test- the test to identify any past infection
Antibody tests or serologic tests are done for the detection of any past infection.
How the sample is taken- A blood sample is taken for the result.
How does it work– The test identifies the presence of antibodies produced in the body to fight against the infection. It might not tell about a present infection but it can accurately detect whether a person had an infection in the past or not.
Accuracy of Antibody test– The test is accurate after a keratin time only because the immune system takes time to produce antibodies.
It can up to a few days for the results to come.
We have come a long way in identifying the newly identifies infection in such a short period. There are many tests in the market by many companies and they are almost accurate enough to identify the COVID-19 infection in the body. Although, the accuracy of any test is not 100% and it cannot even be because accuracy is affected by many factors like samples, the testing process, and the time of testing, handling of the sample.
So, in keeping the risk of false results one should either take professional guidance or monitor their condition to choose the best COVID-19 test for themselves.
Dr. B. Lal Clinical Laboratory gives complete guidance and all testing facilities for COVID-19 tests. Contact us for more information or any query related to COVID-19. Our doctors would do their best to help you.