When is a COVID 19 diagnostic test required?
Diagnostic testing for COVID-19 is conducted to find out whether a person is infected with the SARS-CoV-2 virus, responsible forCOVID-19 infection. Your healthcare practitioner may recommend you the same if:
- You are experiencing symptoms of COVID 19 such as high fever, cough,shortness of breath, excessive fatigue, etc.
- You have long-term health conditions such as asthma, heart diseases, etc and experience a sudden worsening of symptoms.
- You have come in contact with someone tested positive for COVID 19 recently.
- You are a healthcare worker working in a hospital environment.
- You require hospitalization for treatment or surgery of existing medical conditions.
What are the different laboratory tests available to diagnosis COVID 19?
In general, there are two types of tests for diagnosing COVID-19 namely, Antigen or Rapid testing and Molecular or PCR testing. The antigen test is often used as a point-of-care test, less expensive and yields quicker results within minutes. However, there is a higher chance of false-negative results as compared to molecular testing. Molecular testing yields more accurate results but are time-consuming.
How is Antigen test performed and what does it reveal?
A sample fluid is collected froma nasal or throat swab and tested for the presence of SARS-CoV-2-specific protein known as antigens. During the test, the sample is applied on the test strip and a positive test result suggests that a person is actively infected by COVID 19.
This test is most accurate when the viral load is very high.
How to interpret an antigen test result?
The antigen test is highly specific implying that a positive test needs no further confirmation. However, they lack sensitivity and may yield false-negative results. Thus, a negative test result may require further confirmation through PCR technique to understand if a person is truly free of the infection.
How is a molecular test performed and what does it reveal?
A sample fluid from nasal or throat swab, seldom from saliva is collected and then processed and tested for the presence of SARS-CoV-2 genetic material known as ribonucleic acid (RNA). This technique involves the extraction of the viral RNA from the sample fluid, conversion to deoxyribonucleic acid (DNA) and its amplification using polymerase chain reaction (PCR) method.
How to interpret a Molecular test result?
A positive test result indicates that the person is actively infected with SARS-CoV-2 virus. The molecular test may yield a false negative result (fail to detect positive cases) in few patients, if the amount of viral RNA is too low in a sample for the detection or if the test is not performed appropriately.
What should I do if my test result is POSITIVE?
A positive antigen or PCR test means COVID-19 virus is active inside your body.You are recommended to isolate yourself, wear a mask, maintain social distancing, and take leave from work. It is also important to take medications as advised by your doctor and keep a constant check on your symptoms. Any worsening symptoms should be promptly reported to the physician for medical advice or you can call for a full body checkup at home
What does it mean when my test result is NEGATIVE?
A negative antigen test should be further confirmed by PCR test. A negative PCR test indicates that youare free from COVID-19 infection. However, there is a small possibility of a false-negative result. It is very much important to understand that a negative test result does not make you immune to the virus. You may still get the virus. Thus, it is advised to wear a mask, wash hands properly, avoid the crowd, and follow social distancing to keep yourself and the community safe from COVID-19.
Do I need a Doctor’s prescription for COVID 19 testing?
No, a doctor’s prescription is not mandatory to get yourself tested for COVID 19. If you are suspecting COVID 19 then, it is always a good idea to get yourself tested, also you can have your medical tests at home at the earliest to enable early treatment and also containing the spread of the virus.
Can I get tested even if I don’t have symptoms?
Yes, you can choose to test yourself if you wish to, even in the absence of symptoms. Testing will avoid the risk of spreading the virus to others.
Is there a need for repeat testing after home isolation or hospital discharge?
No, as per Government guidelines, there is no need for testing after 10 days of symptom onset and no fever for 3 days post home isolation or hospital discharge.
However, critical patients are recommended to tested negative once by the PCR test after the resolution of symptoms.