Yao Pei, a high school headmaster, was not in the mood to enjoy the eight-day National Day vacation.

Before the vacation, he attended several meetings held by the local education department.

"They warned us of potential A/H1N1 influenza outbreaks among students when they come back from the holiday," said the schoolmaster based in Taiyuan, capital of northern Shanxi Province.

This year's National Day holiday concurs with Chinese traditional Mid-Autumn Festival which falls on October 3. This brings Chinese an eight-day break, from Oct. 1 to 8, the longest public vacation.

Also, this year marks the 60th anniversary of the founding of People's Republic of China. Various celebrations are staged during the holidays.

Feng Zijian, director of the disease control and emergency response office with the China Center for Disease Control and Prevention, said unprecedented domestic and outbound travels and mass gatherings during the holidays increased the risk of group infections of A/H1N1 flu.

In mid September, the Ministry of Education issued a circular warning schools of high risk of group infections and asking them to spare no efforts in prevention ahead and after the vacation.

"We have well educated students about how to prevent flu infection and suggested them not to travel to flu-hit regions. We also plan to record every student's health conditions after they return," Yao said. "But I am still worrying."

He has a good reason to worry. In the past two months, the Chinese mainland reported 188 group infections, accounting for 90.8 percent of all group infections since the beginning of pandemic. And among them, 179 cases occurred in schools or on school-related activities, according to the Health Ministry.

Several universities in Shandong, Heilongjiang, Sichuan and Shaanxi provinces have decided to cancel the eight-day break for students.

"The holiday is long and students would go back to their hometown or out for tourism," said a teacher with the Qingdao Agricultural University in Shandong, in explanation to the decision. He noted that the flow of students would make it hard for the school to fend against A/H1N1.

To make up for the loss of students, the schools decided to lengthen the upcoming winter holiday.

While Yao's holiday is overshadowed by the flu, most Chinese show no signs of compromising their vacation plans.

Jiang He, a 25-year-old magazine editor, is taking a trip in western provinces of Ningxia and Qinghai.

"It is a pity not to make good use of this long holiday," she said.

During the holiday, 64 million people, almost the same population as France, are expected to travel by trains within China, a year-on-year rise of 9.3 percent, said Wang Yongping, spokesperson of Ministry of Railways.

Many are rushing back for family reunion as the Mid-Autumn Festival is traditionally for family to get together, and some are sightseeing across China.

Since A/H1N1 is highly transmissible through respiratory droplets, crowded trains could be risky.

Vivian Tan, spokesperson of World Health Organization China Office, said, "The risk of infections is all around us, and what we can do is to take simple measures to protect ourselves."

Beijing government has started vaccinating local residents. Around 10,000 paraders on the National Day celebrations are vaccinated for free.

But many seemed not to be precautious.

On a train bound to Taiyuan in northern Shanxi Province from Beijing on Thursday, two out of 75 passengers in a carriage were wearing masks.

"I don't think the flu is horrible so I take no preventions against it in my trip," Jiang said.

"So far, most cases have been mild, but we are concerned that there could eventually be more severe cases emerging," Tan said.

China had seen a relatively small number of A/H1N1 cases compared to its large population but the number had increased sharply in recent weeks, she said.

As of Sept. 30, China has confirmed 19,589 A/H1N1 cases and the figure was 10,221 on Sept. 16, a rise of 92 percent. No fatal cases were reported, according to the Health Ministry.

"Still we cannot cancel gathering or postpone travel indefinitely, especially since pandemic usually last 1-2 years. Life cannot come to a standstill, or social-economic losses would be enormous," Tan said.