With the increase in Covid-19 cases, many state governments across the country have started conducting rapid antigen tests to speed up the process of testing.
The Indian Council of Medical Research (ICMR) had previously approved the use of Rapid Antigen Tests (RAT) kits for the detection of Covid 19. The test uses nasal swab samples for detection and can be performed outside laboratory settings. The kit is able to give quick results in about 30 minutes so it will be possible to conduct large number of tests. The Rapid Antigen Tests (RAT) will be conducted in both Covid 19 hospitals and containment zones. According to ICMR guidelines the test needs to be conducted under strict medical supervision and the kit temperature need to be maintained between 2 to 30-degree Celsius. Also, after the collection of the sample, the test needs to be conducted within an hour for a correct and effective result.
The test can be used on different categories of patients – Patients with influenza like symptoms and suspected of being infected with covid 19, Asymptomatic patients who are hospitalised and belong to high risk groups with other comorbidities, and Asymptomatic patients undergoing surgical/non-surgical procedures like dental surgery, dialysis etc.
It has been pointed out that the rapid tests are very specific to the virus but not as sensitive as RT-PCR (Reverse Transcription Polymerase Chain Reaction) tests. ICMR guidelines suggest that patients getting positive results can be considered a true positive while patients getting negative results should be tested following a RT-PCR method for a reconfirmation. SD Biosensor, the company which has been allowed by the ICMR to manufacture the test kits suggests that a negative result may be possible due to either a poor-quality specimen or if the concentration level of the antigen in the specimen is lower than the sensitivity of the test. There is also the possibility of difference in sensitivity between individuals of different age groups.
Many states including Madhya Pradesh, West Bengal, Andhra Pradesh and Delhi have started with these tests. The Madhya Pradesh government has planned to increase the number of testing to 2500 per day with the introduction of the rapid tests in the state capital Bhopal. Once the tests give good result it will be implemented in other districts as well. Previously RT-PCR test method was being used to conduct tests which required a laboratory setting and was more time consuming. Using the more simplified rapid antigen testing method and as a part of the ‘Kill Corona’ campaign the government has decided to reach out to larger sections of the society. The West Bengal government has also started using rapid antigen test kits. State minister Firhad Hakim has introduced the rapid antigen testing in parts of South Kolkata where about 50 people underwent the test. According to him these kits will help in detecting the infection in a speedy manner. According to Kolkata Municipal Corporation (KMC) officials the tests will be conducted across 16 boroughs of the civic body. From the results the positive reports were also sent to the health department. Rapid tests were also conducted across Delhi, but the Arvind Kejriwal government had been pulled up by the Delhi high court for over dependence on the tests. This is because the Delhi government had asked all healthcare facilities to conduct RAT testing on individuals having a ‘high risk’. It has been said that the Rapid tests are quicker but not as reliable as the RT-PCR tests. The RAT tests have a possibility of giving false negative reports. If the test results are positive, one can be sure of the result but in case of negative results there is a possibility of the results being false, so one cannot entirely rely on them. All patients getting negative reports need to be examined once more with the RT-PCR method.
While the RAT testing has led to high number of tests, the issue of false negatives is something to be concerned about. As a result of the mixed reactions on the RAT tests it is yet to be known whether they can be used a reliable method of testing in future.