Why is tracking travel history important for COVID-19?

The recent outbreak of the disease COVID-19 has rattled the population all over the world. Studying the early transmission dynamics of the infection and evaluating the control measures being taken is an absolute necessity required for assessing the potential of transmission to occur in new areas. The first outbreak in almost all countries had a history of travel to Wuhan or was in close contact with the person who had the travel history. 

One of the major strategies for containing the infection was to impose travel restrictions. However, with respect to experience with past respiratory diseases, travel restrictions have a limited effect. It is brought to light that since only 5% of the infection has been identified, even a travel reduction known to be 99% effective may reduce the epidemic outside the Wuhan region by no more than 25%.