ICMR suggests testing of pooled samples
Council’s advisory is aimed at increasing the numbers of tests conducted by laboratories
- Stating that the number of COVID-19 cases in India is rising, the Indian Council of Medical Research (ICMR) is now advising the feasibility of using pooled samples for molecular testing of patient samples.
- The council has said that it is critical to increase the numbers of tests conducted by laboratories.
- Positivity rate in cases is still low. Hence, it may help to use the pooled samples for screening.
- A pooled testing algorithm involves the PCR screening of a specimen pool comprising multiple individual patient specimens, followed by individual testing (pool de-convolution) only if a pool screens positive.
- As all individual samples in a negative pool are regarded as negative, it results in substantial cost savings when a large proportion of pools tests negative.
- The ICMR has noted that a feasibility study was conducted at DHR/ICMR Virus Research and Diagnostic Laboratory (VRDL) at King George’s Medical University (KGMU), Lucknow.
- It has now recommended sample pooling for real-time RT-PCR screening for COVID-19 (based on the KGMU study).
- The study has recommended that it should be used only in areas with low prevalence of COVID-19 (initially using proxy of low positivity of less than 2% from the existing data).
- In areas with positivity of 2-5%, sample pooling for PCR screening may be considered only in community survey or surveillance among asymptomatic individuals, strictly excluding pooling samples of individuals with known contact with confirmed cases and health care workers.