Large numbers of people appeared at a government hospital in the city on Saturday for Covid-19 tests
BENGALURU: Clubbing of swab samples for pool Covid-19 testing has almost been stopped in the state as positivity rates continue to rise. The approach was adopted in May 2020 to conserve resources and it was phased out last month in Bengaluru and more recently in other districts.
Pool testing is recommended only if a district has a positivity rate below 5 percent. Several districts currently have a quota of more than 20 percent.
In this approach, nasal and throat swab samples from a suspected Covid patient are placed in a liquid medium in a tube. One drop each from four other samples from the same area is pooled and tested. If the cumulative lot is found to be negative, there is no need to test the five samples individually. If the lot is positive, all five samples are tested separately.
Currently, the majority of the samples are processed individually. Lab technicians say this takes more time and resources.
Deputy Prime Minister CN Ashwath Narayan, head of the state’s Covid Task Force, said pool testing would not be conducted because all districts had a positivity rate greater than 5 percent. “The pool tests have dropped dramatically, up to 90 percent. It is only carried out in a few places where the positivity rate is below 5 percent in order to determine the Covid status of the primary contacts. Instead of five samples, two samples are now combined in the laboratories, ”he said.
Currently, Karnataka is testing almost 1.2 lakh samples per day. Experts say the effort should be increased and RAT (rapid antigen test) kits that give results within 30 minutes should be used to determine the status of symptomatic individuals.
“The tests need to be stepped up. If it increases, rapid antigen testing must be performed in up to 30 percent of samples, especially in symptomatic patients. If these tests are negative, RT-PCR tests have to be ordered, ”said the virologist Dr. V. Ravi, who is a member of the State Technical Advisory Committee on Covid-19.
Ashwath Narayan said the government is focusing more on targeted testing than sampling. “Pool tests were done earlier when the positivity rate was low. Now the focus is on testing symptomatic people at the earliest, isolating them and starting treatment, ”he added.
Health workers said there was a shortage of RAT kits. 1.1 lakh tests were performed over a 24-hour period, according to the state Covid-19 bulletin issued on Saturday. Of these, only 8,326 were fast antigens.
Ashwath Narayan said there was no shortage of RAT kits. “We have more than 30 lakh RT-PCR and RAT kits each. We recently received 50,000 RAT kits. We have started the procurement process to purchase an additional 50 lakh RT-PCR kits, ”he said.
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