The department released a testing algorithm on August 21 spelling out use of three methods—RT-PCR, rapid antigen and TrueNat/CBNAAT— for different categories of patients and population. It said patients coming to hospitals with severe acute respiratory infection (SARI) or influenza-likeillnesses (ILI) and in need of immediate hospitalisation should be tested with the rapid antigen test that gives an outcome in 30 minutes. And if the result comes negative, an RTPCR should be carried out next. High-risk contacts and low risk symptomatic contacts of positive person, elderly, new mothers, malnourished children, symptomatic healthcare workers should all be tested with antigen first, it said. In this group, a negative test in a symptomatic person should be followed with an RT-PCR.
The RT-PCR, considered the gold standard for diagnosing Covid-19, will continue to be the primary method of testing for symptomatic interstate or international travellers. The protocol said TrueNat/ CBNAAT tests, widely used for diagnosis of tuberculosis before Covid-19, can be used before emergency and elective surgeries, or before delivering a pregnant woman from a containment zone. Hospitals that don’t have access to these tests can use rapid antigen.
Public health secretary Dr Pradeep Vyas said where immediate results are needed to decide on isolation and other measures, a rapid antigen test is preferred, otherwise SARI and ILI case would deteriorate in 24 to 48 hours.
Testing in Maharashtra picked up in July when rapid antigen tests were introduced. Rapid tests now constitute 50% of the tests carried out in the state daily, which is in the range of 70,000-75000.
Dr Vyas said RT-PCR was, however, the primary test in Maharashtra and that efforts were being made for use of installed capacity. The state as on Sunday carried out 36,16,704 tests; Tamil Nadu and UP have carried out over 42lakh and 45 lakh tests respectively. A senior official concurred that testing has been languishing in the state and use of RT-PCR labs is far from optimal.
In some districts, for instance Aurangabad, which is conducting the highest tests per million, it is rapid antigen testing which is largely used, mostly at entry points. The circular on testing has said traders or random asymptomatic visitors should not be tested. Further, it highlighted that in several zillas, one patient was being tested twice of thrice, which was increasing the load on government facilities and increasing expenses. Also for admission to a mental health institution, it advised a 7-day quarantine followed by antigen testing, based on which it will be decided to shift them to a ward or a Covid facility.