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What is pool testing of Corona?
What to study?
For Prelims and Mains: What is it? How it is carried out? Significance and challenges?
Context: 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. The advisory is aimed at increasing capacity of the laboratories to screen increased numbers of samples using molecular testing for COVID-19 for the purpose of surveillance.
How does it work?
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.
What the ICMR has recommended?
- As per ICMR, preferable number of samples to be pooled is five, though more than two samples can be pooled, but considering higher possibility of missing positive samples with low viral load, it is strongly discouraged to pool more than five samples, except in research mode.
- Also, 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 (in direct contact with care of COVID-19 patients).
- Sample from such individuals should be directly tested without pooling.
Why we need pool testing?
- This will reduce the total test kits used to examine patients and treat them.
- It is also expected to trim the work at the laboratories testing these samples.
- International researchers suggest that pooling test samples is cost effective, especially for the countries with limited resources.
- It can be used to prevent community spread of the disease.
Sources: the Hindu.
