Given that every new chain of domestic infections can be traced to the novel coronavirus being imported, it has become extremely important that greater efforts are made to cut the transmission channels by which the virus is entering China from overseas.

The sudden burst of infections in the coastal city of Dalian, Northeast China's Liaoning province, once again points to cold chains being a channel for the virus to spread from place to place, as this wave of infections was traced to a freezer in the city. This is the third local wave of infections that has been caused by the virus being transmitted by the cold chain.

Two hundred and sixty-seven cases have been identified in the 12 days from Nov 4 until Monday. On Zhuanghe university campus alone where the freezer is located, more than 60 students and teachers were infected in just three days.

Dalian is the largest port for imported seafood in the country, handling nearly 70 percent of the country's imported cold chain food and its freezers with a total capacity of 450,000 metric tons keep in storage one-third of the country's cold chain products. The number of people involved in the industry totals about 600,000 in the city.

As a result, it is a great challenge for the city to do a good job in tightly controlling its cold chain logistics to prevent virus from entering the country from overseas through cold chain food packages.

The city has made great efforts since the end of 2020 to tighten prevention and control measures over the port and all freezers. It has stipulated that any cold chain food must be disinfected at a designated freezer immediately after they are unloaded from ships. No cargo of cold chain food is allowed to be taken out of a freezer without being disinfected.

All those who are working at the port or in freezers must strictly follow prevention and control measures to make sure that they do not get the virus from any cold chain food packages. Nevertheless, the latest wave of infections suggests that there must be loopholes somewhere or there must be some people involved who have failed to strictly abide by the rules.

To err is human, so prevention and control measures need to be further tightened at the port. Every link of the work from the unloading of cold chain products from ships to their disinfection in designated freezers and the management of every freezer needs to strictly adhere to the prevention and control procedures. Details make the difference. To err on the side of caution, even if that might seem to be overkill, in the management of the port and freezers is the only way to prevent the transmission of the virus from cold chain products.