Updated: May 4
by Dr. Osama Ummer
What is pooled testing/pooled sampling strategy?
Pooled testing is basically testing multiple swab samples using single Reverse transcription polymerase chain reaction (RT-PCR) test. The technicians only take a portion of the swab sample and combine it with swabs from different people and then run the test. Based on labs in the Germany, Israel and USA you could potentially combine five, 10, 16, 32 or even 64 people’s samples together. This is also called as pooled sampling and has been used previously in the early stages of the HIV epidemic when PCR costs were high.
Benefits and why it is important to India?
In India the main grumble is that many test kits are going waste due to low positive numbers. This has been Government’s prime reason to testing more people, especially asymptomatic ones. India is grappling with number of testing conducted per day and low rate of positive cases, whereas countries like Germany is testing around four lakh tests per day using pooled testing. This technique will immediately give us a better picture about the number of people actually infected without reducing the quality of detection.
“This makes it possible for the implementation of expanded testing in larger population groups as demanded by all scientists and also politicians to be carried out sooner than previously thought, even in view of limited test kit resources,” says Prof. Seifried, lead researcher of German Red Cross Blood Donor Service.
The pooled testing has no influence on the detection limit and if test is negative, all included samples have a reliable negative result. However, if the result is positive, individual testing is to be carried out in previously reserved samples. The positive sample can then be identified within four-six hours. This method can significantly improve the capacity to test in a low-resources setting.
"We found that the use of a pooled testing strategy could reduce the time, cost, and resources required whilst identifying infected people in a population and estimating the infection rate. This would allow us to identify community clusters for targeted public health interventions,” says Ramanan Laxminarayan, CDDEP Director and Senior Fellow.
To continue efficiently with testing, tracing and treating it is vital to implement this strategy and widen the screening tests, especially among communities, people under home quarantine, secondary and tertiary contacts, health workers, police, firefighters, community volunteers, and other administrative employees. As we are moving forward to slowly ease the lockdown which is in force till April 14, 2020 we would have to test more people and identify more cases.