  Contact tracing and quarantine programs have been one of the leading
Non-Pharmaceutical Interventions against COVID-19. Some governments have relied
on mandatory programs, whereas others embrace a voluntary approach. However,
there is limited evidence on the relative effectiveness of these different
approaches. In an interactive online experiment conducted on 731 subjects
representative of the adult US population in terms of sex and region of
residence, we find there is a clear ranking. A fully mandatory program is
better than an optional one, and an optional system is better than no
intervention at all. The ranking is driven by reductions in infections, while
economic activity stays unchanged. We also find that political conservatives
have higher infections and levels of economic activity, and they are less
likely to participate in the contact tracing program.
