- Why in News- At a time when COVID19 cases in the country are seeing a sustained spike, 23 States and Union Territories have testing rates that are even lower than the current national average of 100 tests per million people.
- The Health Ministry urged all States to swiftly ramp up testing and also increase the share of RTPCR tests, which offer more accurate results.
- According to data released at the review, 4,188 average daily cases were recorded in India in the week, in comparison to just 571 daily cases three weeks ago.
- The weekly positivity rate is now at 3.02%.
- Much of the surge is located in eight States; in Kerala, Maharashtra and Delhi, 10 or more districts are reporting positivity rates above 10%; apart from these, Karnataka, Himachal Pradesh, Tamil Nadu and Haryana also have more than five districts reporting positivity rates above 5%.
- RT-PCR Test
- Kary Mullis, the American biochemist invented the PCR technique. He was awarded the Nobel Prize for Chemistry in 1993.
- Under this, copies of a segment of DNA (deoxyribonucleic acid) are created using an enzyme called Polymerase.
- The ‘chain reaction’ signifies how the DNA fragments are copied, exponentially — one is copied into two, the two are copied into four, and so on.
- A fluorescent DNA binding dye called the “probe” is added to DNA, which shows the presence of the virus on a fluorometer.
- However, coronavirus is made of RNA (ribonucleic acid).
- Therefore to detect coronavirus, RNA is converted into DNA using a technique called reverse transcription.
- A ‘reverse transcriptase’ enzyme converts the RNA into DNA.
- Copies of the DNA are then made and amplified.
- Rapid antigen detection test (RADT)
- It is a test on swabbed nasal samples that detects antigens (foreign substances that induce an immune response in the body) that are found on or within the SARS-CoV-2 virus.
- It is a point-of-care test, performed outside the conventional laboratory setting, and is used to quickly obtain a diagnostic result.
- Like RT-PCR, the rapid antigen detection test too seeks to detect the virus rather than the antibodies produced by the body.
- While the mechanism is different, the most significant difference between the two is time.
- As the ICMR has pointed out, the RT-PCR test takes a minimum of 2-5 hours including the time taken for sample transportation..
- In a reliable rapid antigen detection test, the maximum duration for interpreting a positive or negative test is 30 minutes.
