Three main types of COVID-19 tests

The world desperately needs a vaccine and for that, we need more accurate tests. The more number of tests are conducted, the more accurate result we can have, and the faster will be the test kit designing. This would also speed up the clinical trials, check for its effects, start its supply, and make it available to the rest of the world.
Currently, there are three main tests of coronavirus which have been elaborated below.

PCR TESTS
Polymerase Chain Reaction (PCR) tests are very common and the most accurate test to determine if a person is infected or not. This test works by starting with a throat or nose swab using a long and thin nasopharyngeal swab which is stored in a sterile condition and sent to a lab. Lab technicians extract the unique genetic material of the virus from the specimen. The entire solution is placed in a machine. If the patient’s specimen contains the virus then the genetic material is amplified and the machine will show a positive result. This whole process might take up days, but if the hospitals and clinics are equipped with test kits, the time to get the result becomes shorter.

In the US, nearly 1 million people have tested positive using the PCR test. The drawback of this test is that the Center for Disease Control and Prevention’s test had a lot of problems which caused the delay. Currently, the primary hold up is because of the requirement of specialized supplies, expensive instruments, and expertise of lab technicians. The sudden demand for the PCR tests and shortages in the supply chain is another reason for the hold-up.

ANTIBODY TESTS
Antibody tests are also known as serology test detects whether a person has the antibodies in their immune system to fight off the virus. This test is performed on a blood specimen. The blood can be drawn by pricking the finger or taken directly from the vein. A trained expert examines the blood specimen for the antibodies specifically targetted to coronavirus. However, seven different types of coronaviruses can cause illness in human bodies, including those that cause mild symptoms. For each virus, our body prepares different antibodies, and separating the COVID-19 antibody is quite a challenge.

Wider antibody testing will help the researchers know how widely the virus has spread in the population and would help them know about the number of people recovering from the novel virus. The testing will help in deciding who is immune to the virus and who may resume their work at offices without catching the infection against as they will have developed some protection.

The accuracy of these tests is doubtful. The Food and Drug Administration (FDA) issued a policy to allow antibody tests to go to market without reviewing if only they met certain standards and conditions. This led to a lot of unreliable tests and uncertainty amongst the health officials. Inaccurate results would have deadly consequences.

ANTIGEN TESTS
Antigen tests are a quick and easy way to look for a specific antigen – a foreign substance, like a virus or bacteria. Antigen tests are inexpensive and give results in a few minutes. While theoretically, it sounds good, there is not yet a reliable antigen test as of yet.

In a coronavirus antigen test, a bodily sample such as a throat swab is put onto a specifically treated strip, which uses color or marker to detect the presence of the virus. The test looks for a unique part of the virus if that is found in detectable quantity, the test results in positive.

Antigen testing will provide in immediate answers regarding whether the person is infected or not and can be mass-produced, theoretically.

The antigen tests so far don’t work consistently. The ability to detect the virus correctly ranges between 34%-80% according to WHO.
This can lead to missing out on COVID-19 infected patients. Also, designing such tests is difficult as the viruses may have special protein modifications on their surface, which might interfere with the process.

The PCR tests amplify the virus’s genetic material from small amounts, but for antigen testing, the larger amount will be required.