Many positive cases may be negative

‘A few labs did not follow correct procedure to conduct pooled samples tests’

Doubts raised by an expert committee after examining a report based on inspections on private laboratories in Telangana, where COVID tests are conducted, could mean that a few people would have been ‘diagnosed’ positive for the virus though they are actually negative.

Four teams of microbiologists and other officials inspected 16 private labs in city on Thursday and submitted a report that was published in the medical bulletin on Friday. Apart from discrepancies in data submitted by labs, the expert panel suspected that a few labs did not follow correct procedure in conducting pooled samples tests.

According to ICMR advisory, five samples can be pooled for tests. The pool will be considered as one sample. If the pool tests negative, all five samples are regarded negative. If the pool tests positive, then all five samples have to be tested individually to determine all positive cases. The panel also found out that some labs conducted pool testing and when a pool tested positive, all samples were declared positive without doing individual testing leading to some negatives also declared as positive. “It will be studied by experts using amplification plots generated by RT-PCR machine,” the report states.

Since these lab reports were not mentioned in the bulletin, it opens the possibility that those were declared positive after tests could have second opinion about their results. Some other major findings include clear evidence that staff conducting tests in some labs have not been trained properly in RTPCR testing. “Measures for quality control and validation were not followed in some labs,” it states.

“It is unfortunate that the expert committee reported that facilities are inadequate. The exercise done now should have been done before,” said professor of Public Health, School of Medical Sciences, UoH, B.R. Shamanna.

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Printable version | Jul 5, 2020 6:03:35 AM | https://www.thehindu.com/news/cities/Hyderabad/many-positive-cases-may-be-negative/article31936196.ece

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