CURRENTLY diagnostic laboratories in Pakistan are pooling suspected Covid samples for conducting more testing in less time. In this process, samples from multiple suspected patients are mixed and run as one sample, saving a lot of time and reagents specific for the test. These tests require certain amount of viral nucleic acid to be present in the sample for giving a positive result. Such pooling may not provide the required amount of viral nucleic acid for giving a positive result, enabling the suspected patients to continue with their daily lives.

Pooling enables the laboratories to run increased number of samples at the cost of just one while continuing to take thousands of rupees from each suspected patient. Laboratories are not sure about their results, and only when a pool gets a positive response, they go for re-sampling which causes delay in providing the diagnosis.

Real-time Polymerase Chain Reaction (PCR) is a standard diagnostic test for detecting coronavirus in patients showing Covid-related symptoms. Pakistan, being a developing country, has no readily available Biosafety Level 2 (BSL-2) laboratories, which is the minimum requirement for conducting such tests for diagnostic purposes.

The pandemic has forced the laboratories to start these highly specialised tests in their rudimentary basic pathology laboratories. Government facilities are being bombarded with hundreds of samples on a daily basis with very less reagent kits available.

This test provides a lucrative opportunity for private laboratories to earn massive money in a very short time. This pooling strategy is a way to lessen the burden even if it means compromising the test specificity, which, even with variables set to standard, is about 70 per cent.

Policy and framework should be devised for monitoring PCR testing for Covid diagnosis as substandard practices can account for significant increase in the number of patients.

Sarmad Mehmood
Islamabad

Published in Dawn, April 10th, 2021