To reduce the load on laboratories, the Indian Council of Medical Research (ICMR) has recommended an advisory for COVID-19 testing during the second wave of the pandemic.
The advisory stated that the RT-PCR test must not be repeated in any individual who has tested positive once either by RAT or RT-PCR and that testing is not required for COVID-19 recovered individuals at the time of hospital discharge in accordance with the discharge policy of the Ministry of Health.
"The RT-PCR test must not be repeated in any individual who has tested positive once either by RAT or RT-PCR," the ICMR advisory stated.
"The need for RT-PCR test in healthy individuals undertaking inter-state domestic travel may be completely removed to reduce the load on laboratories," the advisory recommended.
Non-essential travel and interstate travel of symptomatic individuals (COVID-19 or flu- like symptoms) should be essentially avoided to reduce the risk of infection and that all asymptomatic individuals undertaking essential travel must follow COVID appropriate behaviour, it stated.
An unprecedented upsurge of COVID-19 cases and deaths is currently being witnessed across India. The overall nationwide test positivity rate is above 20 per cent, the ICMR said.
ICMR has recommended no RT-PCR tests if:
- A healthy individual is undertaking interstate domestic travel. While this is a requirement imposed by states, ICMR said this can completely be removed to reduce the load on laboratories.
- An individual has tested positive by rapid antigen test.
- An individual has tested positive once by RT-PCR test.
- One has completed 10 days home isolation period with no fever for the last three days.
- At the time of hospital discharge.
Advantages of RT-PCR test
The RT-PCR (Reverse transcription-polymerase chain reaction) tests, detects the presence of viral Ribonucleic acid (RNA). It is very accurate and efficient. This test is able to detect a COVID-19 infection even before the person becomes infectious and will allow early isolation. Thus, this method is able to prevent the transmission of the virus to other hosts.
As per experts, RT-PCR test has a specificity rate (ability to identify those without the disease) of nearly 100%, whereas the sensitivity rate (ability to identify those with the disease) of about 67%. This means, RT-PCR test will not give false positives but there are 30-35% chances of getting false negatives.
Disadvantages of RT-PCR test
The disadvantages are the financial cost compared to the antigen tests, the longer evaluation time, and the need for highly professional staff for sample handling.
At the initial stage of the Coronavirus pandemic, RT-PCR test was priced at Rs 4,500 but now the cost has been brought down to Rs 2,500. It is still expensive and takes a day to give results.
Advantages of Rapid Antigen test
The Rapid Antigen test, detects viral proteins. The rapid antigen test reveals patients at the peak of the infection when the body has the highest concentration of these proteins. Rapid Antigen Tests (RAT) has helped in a substantial increase in testing in the country and especially in the national capital Delhi.
Their advantage is the price, the result within 30 minutes and lower demands on the expertise of the staff.
Disadvantages of Rapid Antigen test
However, it’s a known fact that RAT can give a high number of false negatives. A few months back, the Delhi High Court pulled up the Delhi's AAP government for choosing Rapid Antigen Testing (RAT), as the primary test of COVID-19 infection over RT-PCR (Reverse transcription-polymerase chain reaction) which is considered as the gold standard for testing.
The disadvantage is that they are not as sensitive (accurate) as the standard RT-PCR tests used to accurately identify those infected. When using them, a significant percentage of those infected pass the test as a false negative. In a few days, these people will spread the virus among others, thinking they are healthy.
