What COVID-19 test is best? Antibody OR RT-PCR?
Now that the COVID-19 pandemic is in place for many months, steps need to be taken to effectively manage an outbreak: conscientious hand washing and elimination procedures, commonly used monitoring with fast turnaround times, and tracing contacts.
None of these is easy to carry for a long time. Yet they are our best bets in combination when waiting for improved therapies and an effective vaccine.
Then, what tests are needed?
There is some uncertainty about several forms of research available. Unfortunately, since this current coronavirus really is current and COVID-19 is a new disease, there is insufficient information on these studies, and the research choices continue to improve.
But here we know what studies have been done to detect a current infection and whether you have the virus before.
Present infection diagnostic tests
There are two kinds of testing: Molecular testing and the Antigen test. If you want to know that you are actually infected with COVID-19 virus.
Molecular tests (also called PCR tests, viral RNA tests, nucleic acid tests)
How is it accomplished? Nasal swabbing, throat swabbing and saliva or other body fluid checking.
Where can this test be obtained? In a clinic, a hospital, in the car, or even at home.
What does the test look for? Molecular studies are searching for genetic material from the virus alone.
How long does it take to produce results? It’s about the potential of the laboratory. The results may be prepared the same day, but typically take a day or two or more. In several areas, delayed turnaround times of up to 1 or 2 weeks were recorded during the entire pandemic, in particular recently.
And precision? False negatives — a test that tells you don’t have the virus if you have the virus actually — can happen. The rate of false negatives reported is as small as 2% and as high as 37%. The false-positive rate – i.e., how often the test says you do not have the virus – should be near zero.
Labour emissions or other issues with how the lab conducted the test are assumed to be the most false-positive findings, not the limits of the test.
The best choice for a molecular test with a deep nasal swab is typical because it has less false-negative findings than other diagnostic tests or samples from throat swabs or saliva. However, people who are in the hospital will take other samples.
You have heard about pooled testing, which incorporates many samples and conducts a molecular examination. This would accelerate the testing of many individuals and decrease the need for tests.
If a combined test is negative, it is said that a negative test is conducted and individual tests are unnecessary. However, if the combined sample tests positively, each sample taken is checked so that the person(s) responsible for the positive combined result may be determined.
In environments with low infections and decrease in number, the majority of the research results are predicted to be negative, this can be especially useful. The combined testing of staff and students could, for example, be an effective strategy in a community where the infection would appear to be regulated and reopening schemes and businesses would be planned.
How is it accomplished? A swab in the nasal or collar.
Where are the tests you can get? In a hospital or office of a specialist (though tests are possibly available at home too).
What does the test look for? In the test, protein fragments (antigens) of the virus are established.
How long does it take to produce results? The technology is similar to a pregnancy test or a simple strep test, with results in minutes.
And precision? The reported fake negative results rates of 50% are not supported by the FDA as a single test for active infection. Antigen tests are not supported. However, as antigen testing is easier, cheaper, and less complicated than molecular testing requires, some experts suggest repeated antigen testing as a rational strategy.
The false-positive antigen test rate is almost zero, according to one test manufacturer. Thus Ohio Governor Mike DeWine’s recent experience, which apparently was false positively checked, is unusual.
Tests for past infection
Antibody tests (also called serologic testing)
How is it done? A sample of blood is taken.
Where can you get these tests? Blood examination clinic or hospital in a doctor’s office.
What does the test look for? These blood tests recognise antibodies that have been developed by the body’s immune system in response to the infection. Although you can not know from a serologic test if you have an infection now, you can reliably recognise the past infection.
How long does it take to produce results? Typically reports are available a few days from now.
And precision? If an antibody test is too early, the findings may be incorrect. This is because the immune system requires a week or two to develop antibodies after infection.
However, the range of false negatives is from 0% to 30% depending on the study and when in the course of infection the test is performed.
Research indicates that antibody concentrations can decrease in a couple of months. And although a positive test on the antibody indicates that you were exposed to this virus, whether such findings reflect an uninfected or long-term protective immunity is still unclear.
The true accuracy of tests for COVID-19 is uncertain
Sadly, the accuracy of all of these studies is not clear exactly. This is for a number of reasons:
- For such tests, we have no accurate measure of accuracy — only a few widely described figures, like the figures above, for false negatives or false positives. False-negative testing provides false hope that, despite being infectious, medication and relief can be postponed. False, even less probable, positive factors may trigger unjustifiable anxiety and unnecessarily cause people to quarantine.
- The careful selection and storage of a specimen can influence the precision.
- All these tests are not authorised by the FDA officially. The FDA has issued authorizations for emergency use to its producers. And that means that the normal thorough research and monitoring did not take place and the reports of accuracy were not published widely.
- These tests are conducted by a large and growing number of laboratories and companies. More than 170 molecular tests, two antigen studies and 37 antibody tests are available at the time of this posting.
- The virus is newer, so all these experiments are new. Exactitude tests can only be estimated without a long track record.
- We don’t have a conclusive measure to compare the “gold standard.”
Unfortunately, it can be confusing to get a COVID-19 test, since the choices are changing quickly and tests are being sold by many businesses. Given the current test limitation, we are fortunate that so early in the course of a newly discovered virus, relatively reliable tests are possible. Imagine where we would be if we weren’t.
Nevertheless, better testing and access to these are required. And as quickly as possible, all tests should be strictly regulated by the FDA. Finally, large-scale tests and fast processing times are important for successful contact monitoring and the control of this virus.
What COVID-19 test is best? Antibody OR RT-PCR?