Testing for tracing or testing just for treating? A comparative analysis of strategies to face COVID-19 pandemic

There is some consensus in Europe and Asia about high testing rates being crucial to controlling COVID-19 pandemics. There are though misconceptions on what means an effective high testing rate. This paper demonstrates that the rate of tests per detected case (Tests/Case) is the critical variable, correlating negatively with the number of deaths. The higher the Tests/Case rate, the lower the death rate, as this predictor is causally related to contact tracing and isolation of the vectors of the disease. Doubling Tests/Case typically divides by about three the number of deaths. On the other hand, the per capita testing rate is a poor predictor for the performance of policies to fight the pandemics. The number of tests per 1,000 inhabitants (Tests/1,000) tends to correlate positively with the number of deaths. In some cases, high levels of Tests/1,000 just mean an epidemic that ran out of control, with an explosion of cases that demands high testing rates just to confirm the diagnosis of the seriously sick. This study also demonstrates that an early tracing strategy, with a high level of Tests/Case, reduces combined costs of testing and hospitalization dramatically. Therefore, the common claim that tracing strategies are unaffordable by poorer countries is incorrect. On the contrary, it is the most adequate, both from the economic and humanitarian points of view.