Testing for COVID-19? Things you should know

What is COVID -19?

Covid 19 is disease caused by SARS CoV 2, which commonly affects the respiratory system, manifest as common flu, pneumonia, or less frequently acute respiratory distress syndrome. The common symptoms associated with Covid 19 are Cough, difficulty breathing, body aches, loss of taste or smell, sore throat, rhinitis, vomiting, diarrhea.

What is the importance of getting tested for COVID 19?

Testing for Covid 19 is important for early diagnosis, so that appropriate treatment can be given and to prevent the transmission of infection.

What tests are available for diagnosis of COVID 19?

SARS CoV 2 is an enveloped single stranded RNA virus and has various proteins. The diagnostic test is based on these structures or antibodies produced against the virus.

The diagnostic tests available are:

1. rtPCR test:

rtPCR or real time PCR method is one of the PCR techniques used in detection of SARS CoV 2 RNA. rtPCR is considered as gold standard for the detection of SARS CoV 2. Swab from nose, throat or both is taken which is transported in VTM (Viral transport media) for the test.

2. Rapid PCR test:

There are few rapid PCR point of care test available which can give result in short time. 
• Abbott ID Now test: It is an FDA (EUA) authorized uses technique of isothermal nucleic amplification for detection of RdRp gene of SARS CoV 2. It can give result as early as 15 min. A dry swab collected from nose or throat is used for the test.
• Xpert Xpress SARS CoV 2: it is also an FDA (EUA) authorized test which is a Cartridge based nucleic acid amplification test (CBNAAT) and can give result in approximately 50 min.

3. Antigen test:

Rapid Antigen test (RAT) which is a rapid lateral flow assay which detects the proteins of the covid virus. This test is used for rapid screening, swab from nose is used for the test. The test can be negative in early or late stage of infection. 

4. Covid antibody test:

 It is mainly used for sero surveillance, which will help in the understanding the immunity and infection present in the population. The sample type used is serum (Blood) sample.

•Covid IgG, IgM test:

Presence of Covid IgM indicates recent infection, presence of Covid IgG indicates infection, immunity, or immunity after vaccination. There are various methods like CLIA, ELFA, CIA, immunochromatography methods which is used for the assay. 

• Spike Protein antibodies: can be present in people who had been infected with Covid or post vaccination as immune response.

There is various test which are available for the detection of Covid 19 at affordable cost, which can be preferred based on the clinical condition and need.