Pooled testing for COVID-19 is being considered as a method to ramp up testing Stat News. Apparently this is being considered by the White House coronavirus team.
It's not clear to me what the goal of this approach is as it seems to be contradictory to the notion of rapidly detecting persons who may be contagious so as to place that person in immediate isolation.
Using the example from the Stat News article, say that a company has 100 employees that need to be "observed" on an on-going basis. Pooling, (as I think I understand it) might consist of taking 100 swabs and combining groups of ten swabs, then subsequently conducting just ten analyses. For the sake of example, let's agree that of the 100 employees only ten employees are actually contagious.
Under the best of circumstances, as luck would have it, all ten of those contagious employees might be in just one pool. In that case 9 of the tests would come back negative and 1 test would be positive. In the worst case, those ten contagious employees are uniformly distributed, resulting in 10 tests all coming back positive. More likely, however, those swabs of the ten infected employees will be randomly distributed among the ten pools.
So, for argument's sake, let's suggest that 5 of the pools are analyzed as positive and 5 pools are negative. Assuming that the analysis is perfect (that is no false positives or false negatives), it would seem that the 50 employees in the 5 negative pools could be deemed safe to return or continue to work. The other 50 employees would have to be retested, either by pools or individually. If they are tested by pools (and the pool size is maintained at 10 swabs per pool), the ten infected employees will still not have been positively identified, making a third round and fourth round of testing a necessity.
The obvious advantage to pooled testing is that a smaller number of analysis could be performed, however the number of swabs (supposedly in short supply). Some non-infected persons will be tested multiple times.
On the other hand, the length of time to detect only those who are infected, will double, triple and possibly quadruple.
So this seems to be a classic case of cost (of testing) versus urgency (to mitigate spread of the virus)
If a company (or county or country) feels an urgency to attempt to isolate infected persons, it would seem sensible to deploy individual (non-pooled) testing. On the other hand, if there is no sense of urgency, then a pooled approach (because it involves less analytical work) is appropriate.
If my perspective or understanding of how pooled testing would be deployed, I certainly would like someone to correct me, in the meanwhile my question is:
What is the principle goal of pooled COVID-19 testing for the United States?