Pooled testing is when samples of several people are combined in a single tube and tested using molecular biology detection methods all at once: if the results from the pool test are negative, all patients in the pooled sample are declared not to have COVID-19; if the results of the pool are positive, each patient sample is tested individually.
The pooled testing strategy is appealing, particularly when test availability and financial resources are limited. Pooled testing was initially developed, in 1943, by Robert Dorfman, an American economist to test US army drafts for Syphilis. The strategy has since then been used to test for sexually transmitted infections, malaria, as well as in blood banking. Pooled testing is most efficient when applied in settings of low virus prevalence. Because if the virus is too widespread it’ll always show as positive so individual testing will have to happen anyway. In African countries, the COVID-19 infection prevalence is still low in comparison to other parts of the world.
For this reason, only a few countries – such as Ghana – have opted to use the pooling approach for massive testing.