As of Tuesday noon, the National Health Commission registered nine newly identified local COVID-19 infections nationwide.

The number itself may not be anything to worry about. Considering all the cases may be associated with a group of eight tourists, all of whom have been confirmed COVID-19 positive, however, it is not groundless to worry that a longer, complex chain of infections may emerge in the days to come.

Since it remains a mystery where and how the first two victims in the group, an elderly couple from Shanghai, became infected, and they have traveled thousands of miles from the coastal metropolis of Shanghai to a number of northwestern localities, most of which are popular tourist attractions, the chain of infections could be difficult to trace and control.

The latest data indicate that dozens of people have been infected, and they are in Beijing, and Gansu, Guizhou, Hunan and Shaanxi provinces, and the Ningxia Hui and Inner Mongolia autonomous regions.

To contain the situation, regional lockdowns have already been ordered, and large-scale screening is underway in multiple places, including Beijing. Some residential neighborhoods and public venues have been put under quarantine and tourist attractions have been closed.

In the city of Jiayuguan, Gansu province, local bus services have been suspended. In several other places, inter-regional public transport has been halted.

It is thought that the initial infections may have been in Erenhot, Inner Mongolia, which is adjacent to a part of Mongolia where the pandemic situation is reportedly serious. But as of now, that has not been confirmed.

If that indeed was the case, it would raise questions about potential local community transmission, which would make things even more complicated. Equally troubling is the fact that the infected group of eight has traveled long distances across provinces, sometimes using public transport, including protracted train trips, and visited many crowded tourist sites and public venues. Tracking their contacts even after diagnosis will be an extremely challenging task.

The National Health Commission and National Bureau of Disease Control and Prevention have sent teams to Gansu, Inner Mongolia, Ningxia and Shaanxi to guide the local epidemic prevention and control work.

This new outbreak spread by a group of tourists, along with the sub-cluster identified in the Nanjing-related chain of infections spanning July and August, should once again remind people of the lingering risks of cross-region travel, and highlight the importance of balancing economic development with epidemic control.

While boosting tourism, which is an indispensable part of consumer spending, to drive the economy, there is a need for sustained vigilance for pandemic control.