Pooled testing has been used in communities with low Covid-19 prevalence to increase testing throughput and enable more extensive surveillance testing.

So far, surveillance testing for Covid-19 in Singapore has largely been targeted at groups such as essential workers and residents of nursing homes, and those aged 13 or older with acute respiratory infections, including cough and sore throat.

With 10 or fewer new daily Covid-19 cases out of about 31,000 daily swabs in the past week, these conditions are arguably well suited for the expansion of pooled surveillance testing to the entire Singapore population.

With a targeted 40,000 laboratory tests per day and a population of 5.7 million, the population may be tested in about a month with a pooled size of five — combining swabs of up to five people into one laboratory test, which does not affect the sensitivity of the tests.   

Research has shown that the pool size may be increased to 32 or 64 with a sufficiently low Covid-19 prevalence rate and an appropriate choice of polymerase-chain-reaction amplification cycles. This could cut the time needed to test the population to less than a week, even with two or three tests per person.

This makes a monthly testing cadence feasible, since pooled-testing protocols typically require more than one test per person. A proportion of tests will also have to be reserved for visitors and others.

Given the low prevalence rate of Covid-19 in Singapore's population, as inferred from present testing data, it is opportune to begin monthly pooled surveillance testing of the entire population.

This will bring peace of mind to the populace — especially among elderly people, who are more susceptible to the coronavirus — and instil global confidence in Singapore’s management of Covid-19, as we move towards the third phase of reopening our economy. 

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