The influenza A (N1H1) has come in to the country in spite of the tightened control at international airports. A day after the first case was confirmed, the second suspected one was reported on Tuesday.

It is not surprising that the flu finally hit China. It is unrealistic to expect that tightened measures at airports will stop the virus from entering the country, given daily trips to and from flu-affected countries and regions.

Yet, if we do an even better job in carrying out the necessary checks and preventive measures besides preparing for every contingency, we can hopefully keep the flu in check.

There are obviously loopholes that need to be plugged before we have an even tighter net for narrowing down the chances of more people being infected.

The second patient reported his case to Ji'nan Center for Disease Prevention and Control while on the train, but the relevant local department still failed to trace all the passengers in the same car with the patient for tests and quarantine.

It would have been easier and safer for local disease prevention and control and healthcare departments to do that when they picked up the flu patient at the railway station than making attempts to contact the passengers at this stage.

There is also enough reason to call on people to act in a responsible manner.

The first flu patient was reported to have symptoms such as a sore throat on his trip back but he failed to report his symptoms to the health department after arrival in Beijing.

The second one, developed fever in Beijing, but rather than go to doctors for help, after two days he set off on a train trip back to his home province.

Had both reported their cases immediately after they had experienced the symptoms, the chances of other people being vulnerable to infection would have been vastly less. Now, should other residents, who happened to travel on the same flights or the same train with either, also refuse to report themselves, there is much more likelihood of the virus spreading.

To be responsible for others is to be responsible for oneself. If no one cares about his or her obligation to follow the rules in the interest of others and society as a whole, we cannot expect that anyone will be safe from an epidemic like this.

Now 32 passengers who traveled on the same flight with the first flu patient are yet to be located. The number of passengers who were exposed to the second one is much larger as he stayed in Beijing for two days and traveled back home by train.

As responsible citizens, they need to let relevant departments know where they are and cooperate with the local healthcare department for necessary medical observation before they are confirmed to be safe from the virus.

Preparedness averts peril. With much higher population density in our cities than in the United States and Canada, it is more likely for the virus to spread among residents.

So it pays to be prepared for the worst.