New Delhi: With a massive rise in the number of cases in areas that are already affected but a lower positivity rate all across the country, the Ministry of Health and Family Welfare has opted for pooled testing in all districts including zero case districts.
The guidelines from the ministry on the pooled testing for Covid 19 have been developed post a feasibility study by the /ICMR Virus Research & Diagnostic Laboratory (VRDL) at King George’s Medical University (KGMU), Lucknow. The study by KGMU has suggested that the real-time PCR for the Covid-19 by pooling up to 5 samples from an area with a low infectivity rate is feasible. The study has suggested the interpretation that all samples in a pool of 5 will be labelled negative in case the pooled sample tests negative while in case of a pooled sample testing positive, deconvoluted testing should be followed which means testing samples in a pool separately.
The ministry has recommended to not pool more than 5 samples for testing to avoid the samples testing false negative. Detailing the guidelines for the pooled testing, the Ministry of Health has recommended the test only for the areas where the cases are less prevalent– less than 2 per cent positivity rate. In areas with a positivity rate between 2 to 5 per cent, the ministry has asked for sample pooling for only in community survey or surveillance among asymptomatic individuals. The ministry’s guidelines have asked to strictly avoid pooling samples of individuals with known contact with confirmed cases, Health Care Workers, and rather their samples should be tested directly by rt-PCR and not by pooling.
As per the guidelines issued by the health ministry, a pooled test for Covid-19 should be done by pooling 5 samples but more than 2 samples can also be pooled for testing. In order to avoid the possibility of missing samples which are positive but with low viral load, the ministry has strongly recommended against pooling more than 5 samples.
The number of Coronavirus infections in the country has surged by 4,213 including 97 deaths in the last 24 hours. Prime Minister Narendra Modi in his meeting with chief ministers on May 11 has asked for a blueprint for after-lockdown strategies. He has also said that complete resumption of oral life and lifting off of the lockdown is not immediately possible.