BSMMU Trial of Gonoshasthya Kit: Report justifies its usefulness
While Bangabandhu Sheikh Mujib Medical University Vice-Chancellor Prof Kanak Kanti Barua verbally spurned the Rapid Dot-Blot test developed by Gonoshasthaya Kendra last Wednesday, calling it "ineffective in detecting Covid-19", the full report justifies and recommends its use as an antibody test.
That the kit is ineffective in detecting antibodies between Day 1 and Day 7 is stated clearly in the report and aligns with BSMMU's own statement.
BSMMU tried out the rapid dot blot kit on a hundred patients who had tested positive for Covid-19 by the RT-PCR method and has had symptoms for less than 7 days. They found that it could only accurately determine an infection in 11 percent of the tests.
But antibodies are created when the body is fighting back and are unlikely to be present in a patient in the early stage of the illness.
According to the results of the BSMMU report, antibodies are precisely what the Covid-19 Rapid Dot Blot Immunoassay Kit detects, albeit with lower "sensitivity" than other antibody tests that are currently being manufactured abroad.
The report shows that the higher the number of days since the onset of the infection, the higher the "sensitivity" of the kit.
"Sensitivity" is calculated as the ratio between the number of correctly identified Covid-19 samples versus the total number of samples identified as positive for Covid-19.
For a hundred Covid-19 positive patients between Day 8-14 of their infection, the kit could detect antibodies in 41 cases and could not in 59.
For 109 Covid-19 patients who are symptom-free for at least 14 days, the test could detect antibodies in 76 cases.
The BSMMU committee recommended that the antibody kit be used for seroprevalence or to assess the proportion of a population which was infected but recovered.
"GR Covid-19 rapid antibody test has about 70 percent 'sensitivity' in convalescent patients," stated the BSMMU report.
It put the "95 percent confidence interval" between 60.19 to 78.16 percent -- which means there is a 95 percent confidence that the sensitivity of the test will once again fall within that range, if the study is repeated. This also means, based on the current data, the report is saying that the sensitivity can be as high as 78.16 percent.
Swiss company Roche's antibody test received authorisation from the Food and Drug Administration (FDA) in May because their test had a 100 percent "sensitivity" in cases that were 14 days post-PCR confirmation.
"We are submitting a letter to the Directorate General of Drug Administration today [yesterday] asking for authorisation for the use of this kit as an antibody test to be used for the purposes recommended," Dr Bijon Kumar Sil, lead researcher at Gonoshasthaya Pharmaceuticals, told The Daily Star yesterday.
The recommendations listed in the report include "usage of the test for diagnosis of Covid-19 in the second week of illness where RT-PCR is not available and in clinically suspected but RT-PCR negative patients."
In order to understand what the test means for the increasing numbers of "suspected" patients seeking treatment but failing to get any without an RT-PCR test result, Covid-19 Rapid Dot Blot Project Coordinator Dr Mohibullah Khondoker was presented with a scenario: a person showing clinical symptoms for more than 8 days, trying to get admitted into a hospital, but does not have a RT-PCR test result. Can the hospital use the GK kit to determine if he has an infection?
"Yes, he can do an antibody test. But if the result is negative, an antigen test should also be done for viral clearance," he said.
As the report states, if the result is negative, it could mean that either the person is not infected at all or that the person is Covid-19 positive, but the rapid dot blot test is not detecting antibodies yet.
Meanwhile, the report also states that if the result is positive, this could mean that the person either has an active infection that their body is fighting or they have had it in the past and have recovered.
Both scenarios open the doors for Covid-19 dedicated hospitals laying to rest the fear of getting infected in hospital.
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