COVID-19: Know all about types of diagnostic testing, procedure, risks

Doctor with a COVID-19 testing kit

Last Updated October 12th, 2020

Importance of COVID-19 diagnosis and testing

Early diagnosis and proper testing are crucial for detecting the COVID-19 infection and treatment of the patients. Your doctor will decide to do a COVID-19 diagnosis and test depending on several factors, especially if you are experiencing any symptoms of the disease.

Factors determining COVID-19 diagnosis and testing

Your doctor may administer a COVID-19 test irrespective of whether you are showing the symptoms of the disease or not. Here are a few pointers that your health care professional will consider to decide whether you need to take the COVID-19 diagnostic test.

  • If you are showing symptoms or signs of the disease
  • If you have been in close contact with a COVID-19 patient
  • You have traveled recently to a place where there is a high risk of community spread
  • The place where you live may also determine whether you need the test or not
  • If you suffer from some chronic illness or have low immunity
  • You have returned from a different city, state, or foreign country and risk exposure to the disease
  • If you work in a medical facility, hospital, or at shelters like a prison or old-age home where people stay in close proximity and regularly come in contact with the inmates
  • You have been hospitalized recently for medical treatment
COVID-19 diagnosis and testing

Symptoms of COVID-19 that require a diagnosis

If you are experiencing mild or moderate symptoms of COVID-19, call your doctor immediately, and seek medical advice. A few symptoms of the disease to watch out for are:

  • High fever or chills
  • Dry cough
  • Sore throat
  • Tiredness
  • Difficulty in breathing
  • Headaches
  • Runny nose
  • Pain in the muscles
  • Loss of taste or smell
  • Decrease in appetite
  • Discomfort/pain in the chest
  • Abdominal pain
  • Bluish tinge on the face or lips
  • Depressive mood

The symptoms of the disease generally occur between 2 to 14 days of exposure to the virus. However, asymptomatic patients may not exhibit symptoms at all but spread the virus to other healthy people. This is why it is important to monitor the symptoms closely. If you have a recent travel history or risk of exposure to an infected person, call a medical professional immediately. In any case, you should make a prior appointment and avoid going to the hospital or clinic as you may spread the disease to others. Early diagnosis will help get supportive care and treatment and most importantly quarantine of such patients to prevent transmission of the disease.

How to prepare for diagnosis and testing of COVID-19?

Healthcare professionals perform the COVID-19 test only on those who have been exposed to the SARS-CoV-2 virus and are showing some or all of the above-outlined symptoms.

Call your doctor, nurse, or medical professional and describe your symptoms. Also, give other related information regarding the disease with details of how you may have contracted the virus. Your hospital or doctor will tell you about the nearest testing center and the precautions you must follow to visit the center for testing.

It is better to visit the testing center alone. On the day of the appointment, wear a facemask as you set out for the testing center. If a friend or a family member is accompanying you, both should have the facemask on and take necessary precautions.

The FDA (Food and Drug Administration) is providing home testing kits to people that have been identified as having COVID-19 symptoms to do the test at home. You can also collect a nasal sample and mail to the authorized laboratory for testing.

What happens during the COVID-19 test?

During the COVID-19 test, the healthcare professional may collect a sample of your saliva and mucus from your nose or throat for inspection. The sample can be taken at the doctor’s chamber or at the nearest testing center. For home testing, authorized personnel will come and collect the sample. Testing will involve the following steps:

  • Your doctor or healthcare professional will take a nasal or throat swab. To take a nasal or throat swab, doctors insert a thin swab with a cotton tip into the nose or deep inside the throat. The tip is brushed to collect the sample of mucus. The aspirated fluid is also collected from the lower respiratory tract for testing
  • Nasal samples are taken from both the nostrils. The swab will be gently inserted inside the nose, rubbed in a circular motion, and then pulled out to confirm there is enough sample for testing. The swabs are placed in a tube and sealed. This sample is sent to the laboratory for testing
  • Many people express discomfort during the nasal and throat sample. In such cases, healthcare providers can take a saliva sample. Patients will need to spit several times in a tube to provide a sample of their saliva. The tube containing saliva is sealed and sent for analysis
  • Blood samples are taken for an antibody test
  • In certain cases, doctors recommend a stool sample for testing
COVID-19 test sample

Will I feel discomfort during the testing?

Some people may feel a little discomfort especially during the collection of the sample from the throat or lower respiratory tract. However, the testing process takes only a few minutes to perform and there are no side effects.

When will I get my test results?

The samples collected in the testing centers are sent to a different location for analysis. So, it may take a few hours or a day to get the test results. In certain cases, it might take several days to get the test reports. Generally, you can get accurate results within 45 minutes.

What are the Types of Diagnostic Tests?

RT-PCR Test

This is the most commonly used test for screening the COVID-19 disease. A throat or nasal swab sample is taken to detect the RNA (ribonucleic acid) virus. The test will ascertain the presence of an RNA virus even before the antibodies are formed in the body. This test is generally helpful to detect the disease during the early stages when the patient may or may not have exhibited the symptoms. The test uses the “reverse transcription” process to convert the RNA into DNA to ascertain the presence of the disease. During the test, a sample is taken from your nose or throat, and then it is sent to the laboratory where it is treated with chemicals in the RT-PCR machine to detect the RNA. This test is extremely helpful to detect the virus in asymptomatic patients. However, the test may come out false negative for the first time. The same test may need to be performed twice on the patient for accurate results.

Rapid Antibody Test

The Rapid antibody test helps detect the virus especially during community spread and can give faster results. The test detects the presence of antibodies in the blood. Antibodies are produced by the body to fight bacteria, viruses, or disease. The presence of COVID-19 antibodies confirms that the disease has infected the patient. This test helps detect a widespread of the disease in containment zones, densely populated areas, migrant workers returning from different states or cities, health workers, police, and other frontline workers. These tests may also come out false positive or negative. In such cases, patients may have to undergo an additional RT-PCR test for confirmation of the virus. A blood sample is taken from the tip of the finger to detect the presence of IgM and IgG antibodies. These antibodies may develop during different stages of the infection.

Rapid Antigen Test

The Rapid antigen test is conducted where there is a mass spread of the disease like containment zones or healthcare facilities and helps to detect the presence of the virus in large groups of people. A nasal swab is used to collect the sample of the virus and gives quick results for early detection of the disease.

Healthcare professional performing nasal swab test for COVID-19

TrueNat Test

TrueNat was used to detect tuberculosis disease and HIV in patients. However, due to the rapid spread of the disease and the increasing number of patients, doctors need alternative procedures to detect the disease. This test is quite similar to the RT-PCR test and works on the same principle. It is used to detect the presence of the E-gene that is found in the SARS-CoV-2 virus. The TrueNat is a chip-based battery-operated machine that is used to detect the gene and gives correct test results. In case there is a doubt, further testing like an RT-PCR test can be undertaken to confirm the test results. Just like the RT-PCR test, a nasal or throat swab is collected and sent for analysis.

CT Chest Scan

A CT chest scan is often used to detect the spread of the disease in infected persons.

What do my test results mean?

Your test results may come out either positive or negative.

Positive Result

A positive test result indicates that you are infected with the COVID-19 disease. Your doctor will prescribe medicines and explain precautions to take care of your health and to prevent the spread of the disease to others. For mild to moderate symptoms, you have to self-isolate yourself for at least 10 days to avoid the spread of the virus. If your symptoms persist or get worse, your doctor will ask you to stay in isolation for a longer time. For asymptomatic patients, isolation time is 10 days.

Negative Result

A negative result indicates that you are not infected by COVID-19. However, false-negative tests are quite common and patients must isolate themselves and take proper precautions like wearing masks, maintain social distancing, sanitize adequately to avoid the spread of the disease. Patients may be required to do a repeat test to confirm the test results.

COVID-19 Tests in Children and Babies

For children and babies, healthcare professionals use a Q-tip swab to take the sample from the back of their throat, tongue, and nostrils. A blood sample from the veins or the fingertip is also possible to collect. The testing is done at a healthcare center or home. Some children and babies may feel uncomfortable during the test. Parents should ideally accompany their children and explain the procedure beforehand. In addition, parents can help children relax during the whole procedure.

Risks of COVID-19 Tests

There are many situations where the samples collected have been inaccurate and the test results have come out false-negative. The results of the Antigen test is far more accurate and reliable but is expensive and is not suitable for mass testing especially in containment zones and areas with a thick population. Many of the tests fail to identify the virus especially during the early stages of the infection. Further, some testing centers lack proper infrastructure and precautionary measures, there is a risk of even spreading the disease to healthy patients.

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