The Cost of Privacy: Welfare Effects of the Disclosure of COVID-19 Cases

South Korea publicly disclosed detailed location information of individuals that tested positive for COVID-19. We quantify the effect of public disclosure on the transmission of the virus and economic losses in Seoul. The change in commuting patterns due to public disclosure lowers the number of cases by 200 thousand and the number of deaths by 7.7 thousand in Seoul over two years. Compared to a city-wide lock-down that results in the same number of cases over two years as the disclosure scenario, the economic cost of such a lockdown is almost four times higher.