Covid-19: Health dept acts as patients skip follow up tests

2 swab sets

A follow up RTPCR test is imperative for negative antigen tests as they can show false negatives 50% of the time. That is, the test’s sensitivity is only 50%. The health department, on August 5, issued a circular to all districts asking them to collect two sets of swabs while administering antigen tests - one nasal swab for antigen test and another set of nasal and throat swabs for a follow up RTPCR test.

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If the antigen test is negative, the swab collection centre is required to send the set of samples collected for RTPCR testing to the testing lab mapped to the collection centre. If the antigen test is positive then the centre is required to discard the swabs.

The decision was taken as the department found abysmally low rates of follow up for symptomatic antigen-negative patients. Data accessed by DH for tests conducted in the past six-and-a-half weeks from June 25 to August 5 from the ICMR portal shows that Vijayapura has a shocking 1% follow up rate of symptomatic negatives tested with antigen tests.

This means that of 817 symptomatic antigen negatives, the district did RTPCR tests for just 10 patients. Ramanagara had 4% follow up rate, Hassan 7%, Chitradurga had 8%, Belagavi 9%, Dharwad 11%, Mandya 16%, Bengaluru Urban 21% and Kolar 22%. Not testing symptomatic antigen negatives who may test positive on RTPCR may lead to these people infecting others.

Bidar District Health Officer Dr VG Reddy said though there are 57 swab collection centres, there is only one Covid-19 testing facility in Bidar Institute of Medical Sciences that can test only 600 samples a day if five samples are pooled at a time. The district has still managed 70% follow up. “We need another 30 lab technicians and data entry operators,” he said.

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Incidentally, the follow up positivity rate in each of these districts was quite high which means if not for a follow up RTPCR test, these Covid patients would not have had a timely diagnosis, treatment and contact tracing. In Vijayapura, it was 20%, Ramanagara 31%, Hassan 33%, Chitradurga 4%, Belagavi 60%, Dharwad 50%, Mandya 3%, Bengaluru Urban 26%, and Kolar 13%.

The test results of an antigen test take only half an hour or more. Health Commissioner Pankaj Kumar Pandey defended the districts saying, “We have done follow up for 40% to 45% cases on an average across the state. They have done the follow up test but due to software issue, a new sample referral form was generated and couldn’t get linked in the
software.”