Context: Recently, the Indian Council of Medical Research(ICMR) recommended the use of Rapid Antigen test kits along with RT-PCR in containment zones. 
About the new test protocol

• The Antigen test kits will allow faster diagnosis and will reduce laboratory examination time. The maximum time taken by the Rapid antigen test to interpret positive or negative is 30 minutes. 
• The individuals who test negative to COVID-19 in rapid antigen test should be tested with RT-PCR  to make sure no threat of virus remains and the individuals testing positive under the rapid antigen test will be considered to be positive.

The Antigen Test is to be used in three categories:-

• Persons showing influenza-like symptoms.
• Asymptomatic patients hospitalized for the treatment of malignant disease, immunosuppressed patients, transplant patients, etc.
• Asymptomatic patients undergoing aerosol and surgical interventions such as surgical procedures, dialysis and bronchoscopy.
• Very few reliable antigen detection kits for Covid-19 diagnosis are available worldwide and the kits to be used in India are developed by a South Korea based company SD Biosensor. 

What is Antigen test?

• Just like the RT-PCR test of COVID-19, this test also detects the virus rather than the antibodies. Antigens are foreign substances that induce an immune system in the body. It uses blood and detects the body’s response to the virus.  

What are the limitations of an antigen test’s results?

• These tests are very specific for the virus, but are not as sensitive as molecular PCR tests. This means that positive results from antigen tests are highly accurate, but there is a higher chance of false negatives, so negative results do not rule out infection.
• Negative results from an antigen test may need to be confirmed with a PCR test prior to making treatment decisions or to prevent the possible spread of the virus due to a false negative.
• Once the sample is collected in the extraction buffer, it is stable only for one hour. Therefore, the antigen test needs to be conducted at the site of sample collection in the healthcare setting.

About Indian Council of Medical Research (ICMR)

• It is the apex body in India for the formulation, coordination and promotion of biomedical research.  
• It works under the aegis of the Department of Health Research, Ministry of Health & Family Welfare. 
• It is assisted in scientific and technical matters by Scientific Advisory Board comprising eminent experts in different biomedical disciplines.
• Its mandate is to conduct, coordinate and implement medical research for the benefit of the Society; translating medical innovations into products/processes and introducing them into the public health system.