Implication of close contact testing in eliminating an epidemic: Application to COVID-19 epidemic in South Korea and New York City

After the first wave of the coronavirus epidemic, temporary stability in the disease spread dynamics was observed in many regions. This behavior can potentially be attributed to the measures implemented to contain the spread, particularly close contact testing. We propose a deterministic mathematical model that simulates the dynamic spread of the disease while considering the actions of the public health system. The developed model achieves a non-forced balance in daily confirmed cases, reproducing the observed epidemic behavior during the COVID-19 outbreak in South Korea and New York City. Our finding indicated that, although the quasi-steady state behavior can only be attained within a certain range of model parameters, an increase in the health system’s interventions does not eliminate the epidemic. We conclude that the observed stationary state of daily COVID-19 cases does not result from setting the basic reproductive number to one. Instead, it emerges as a natural consequence of the policies implemented by authorities to mitigate its spread.