China is awaiting samples of the A/H1N1 virus from the World Health Organization (WHO) to produce its own vaccine, and it could take three or four months, or even longer, to complete the procedure, an expert from the Chinese Center for Disease Control and Prevention (China CDC) told Xinhua on Sunday.

The vaccine would be very important in preventing an outbreak of the disease, said Zhang Yanping in an interview.

The A/H1N1 virus is believed to have originated in Mexico and the United States, he said.

China has developed its own method of making quick tests for the A/H1N1 virus by analyzing nucleic acid, which takes just 12 hours, according to Shu Yuelong, another expert of the China CDC.

The China CDC is training staff from epidemic monitoring stations across the country to do the nucleic acid test, and the reagent will be distributed to all 84 stations, said Mao Qun'an, an official with the Ministry of Health.

The China CDC obtained the sequence of the A/H1N1 virus from the US Centers for Disease Control on April 27 and the primer for making nucleic acid tests from WHO on April 28.

China is working to prevent the A/H1N1 virus from entering the country. It has yet to report a confirmed case.

A 25-year-old Mexican man was confirmed as infected with A/H1N1virus in Hong Kong. He arrived in Shanghai last Thursday on flight Aeromexico 098 and then flew to Hong Kong via China Eastern Airlines.

Most of the other passengers aboard the flight are under quarantine or observation in various parts of China.