The mainland may begin experiencing localized outbreaks of the A(H1N1) flu as infections through domestic transmission continue to rise, the Ministry of Health said in an online statement on Wednesday.

The World Health Organization (WHO) announced late Tuesday it was going to raise the alert level of the epidemic now sickening people worldwide to its top Phase 6 pandemic.

The Phase 6 definition characterizes only the disease's geographic spread, not its severity.

The virus is continuing to spread in China and has infected 111 people on the Chinese mainland, according to the Ministry of Health's tally on Wednesday.

Around 10 percent of the total infections are local cases with the rest imported ones, Health Minister Chen Zhu told Margaret Chan, director-general of the WHO.

"We don't know how long the epidemic will last and when exactly community outbreaks will come," Zeng Guang, a top epidemiologist with the Chinese Centers of Disease Control and Prevention said last week.

"The government has been able to track the original source of each infection," Chen noted.

"The epidemic is still under control in China," Zeng said. But he was also expecting a long-term fight against it.

The mainland had done a good job delaying secondary transmission, first reported on May 29, which helped buy more time for vaccine development and production, according to Zeng. In neighboring Japan, where the H1N1 virus has spread quickly, the first local transmission happened after only four imported cases.

Hong Kong confirmed its first domestic infection yesterday. A 55-year-old man is believed to be infected by a previously-confirmed patient as he had no recent travel history.

The number of confirmed cases in Hong Kong rose to 49 yesterday.

Beginning last week, shipments of seed virus for vaccine from collaborating centers of the WHO began to arrive at the mainland's qualified flu vaccine manufacturers nationwide.

Upon getting the sample, Beijing-based Sinovac Biotech Company, China's leading vaccine producer, announced the start of vaccine production late Monday.

Given a population of 1.3 billion, the production capacity of a single producer falls short of potential national demand. In response, the State Food and Drug Administration, China's top drug authority, has encouraged the mainland's 11 qualified flu vaccine producers to cooperate in technique sharing and production planning to rapidly expand production.

"The ready-to-use vaccine will go to the nation's strategic stockpile rather than drug distributors," said Huo Haiqin, with Zhejiang-based Tianyuan Bio-Pharma, one of the 11 enterprises.

(China Daily June 11, 2009)