Mechanistic transmission models were fitted to the first year of reported COVID-19 cases in 110 countries and combined with GDP-scaled intervention costs and infection costs covering quarantine and mortality, to find the transmission reduction that minimised total cost over 26, 40 and 52 weeks. Cost-optimal average transmission reduction ranged from 31.2% to 57.3%, with a mean excess-cost ratio of 55.2% (median 30.8%). Excess costs were asymmetric around the optimum, exceeding 400% for five percentage points below it against 10-80% for the same margin above it, under the modelled assumptions and in a preprint that is not yet peer reviewed.
Why it is interesting: It puts a cost shape, rather than a single target, on early pandemic intervention intensity, and tests how far national indices such as SDI and GDP per capita track country-specific optima.