Pooled testing can reduce the use of resources, and this strategy can be used in settings where the Covid-19 prevalence is low as well as higher-risk areas like dormitories, said the Health Ministry's director of medical services Kenneth Mak.
Asked about the rationale for such tests at a virtual press conference yesterday, Associate Professor Mak explained that pooled tests involve using one Covid-19 test on a group of suspect cases instead of on one person.
When used for routine testing in the community, such tests are conducted by bringing people in an at-risk group together.
If the pooled test yields a positive result, all the people who were part of the group will then be individually tested to determine who had Covid-19.
In dormitories, however, pooled testing is conducted as part of a series of steps in the process of clearing the dorms of Covid-19, said Prof Mak.
A preliminary screening is often first done in the various dorms to get a sense of whether the prevalence rates of Covid-19 infection in the dorm are high or low, he noted.
Subsequently, if the authorities decide testing in the dorm can continue, workers will be grouped based on their living arrangements, and a pooled test will be conducted on them.
A decision will then be made on whether individual PCR (polymerase chain reaction) tests are required based on the pooled tests, he added.
This is why a higher number of cases from dorms are now being reported, as the authorities are now subjecting those with previous positive pooled tests to individual tests, he said.
PCR technology detects the presence of viral genetic material in patient samples.