The epidemic of Covid-19 is attributed to the spreading virus spurred on by asymptomatic characteristics of the disease and late appearances of symptoms due to a long incubation period. Asymptomatic cases may be diagnosed on the onset of the disease and earlier symptoms appearing during the course of the disease also gives a credible opportunity to make an earlier than usual diagnosis.
In vitro diagnosis (IVD) has played a crucial role in the Covid-19 pandemic for two important reasons; early diagnosis of the infected individual limits the spread of the disease & increases the possibilities of being cured and enhances the survival rate.
The nucleocapsid protein (N ) present in virus genome helps the virus to bind to target cells through the host cell receptor and membrane fusion . The N-protein is the most abundant protein in the virus and it is the one that our immune system usually detects. The N-protein rarely changes along the disease progression and, for these reasons is often used as a marker in diagnostic assays.
The viral nucleic acid-based test using quantitative reverse transcription–polymerase chain reaction (RT-PCR) is the first line screening method of choice for SARS-CoV-2 detection being regarded as the “gold standard” test due to its high sensitivity, rapid detection, and other desirable characteristics. However in case of a higher sample load , Antigen detection using ELISA tests are the preferred choice for timely reporting of the patient results as this will be helpful in ; Reducing transmission rate & Faster Contact Tracing.
The above mentioned points highlight the importance of early adoption of Antigen testing within the ICMR protocol for diagnosing SARS-CoV-2 virus. Apart from being a highly sensitive and selective analytical tool for diagnosis, the Antigen test is an essential component in fighting the pandemic.