Optimal Size of COVID-19 Testing Pools

This research note investigates the optimal size of pools for pooled, COVID-19 testing when positive pools will be followed up by individual tests of pool members. Formulae for the optimum are derived and provided. The analysis indicates that

• optimal pool sizes are unlikely to exceed about 20 individuals in realistic situations,

• optimal pool size is influenced by prevalence in the population and the extent to which infection is clustered within the population, and,

• pools are most efficiently comprised of people with homogeneous risk, with heterogeneity across pools.