Most outpatients have fevers, headaches and sore throats that may be attributable to flu, he said.

Wang Yan, the hospital's respiratory specialist, said she has to work a 24-hour shift on alternate days in response to the rising number of patients. "Sometimes, more than 30 people will be admitted after midnight," she said. "I am exhausted through lack of sleep."

Experts said the number of cases of fl u in Northern China is expected to rise before winter ends. ZOU HONG AND WANG JING / CHINA DAILY

Consulting a doctor is the wise choice for people with serious flu-like symptoms, she said, emphasizing the first 24 hours after the onset are crucial for effective treatment.

A World Bank study in 2008 estimated that a flu pandemic could cost $3 trillion and cause a roughly 5 percent drop in global GDP.

Also, at least 70 million people could die worldwide in a severe pandemic, it estimated.

During the 2003 SARS outbreak, the epidemic halted travel, trade and workplaces and cost the Asia-Pacific region $40 billion, according to the WHO. The six-month-long outbreak killed 775 people in 25 countries.

Vaccination

Vaccination is the most effective means of prevention, said Shu. However, a series of misunderstandings have resulted in less than 2 percent of the Chinese population receiving an annual flu shot.

Wang Quanyi said the virus will continue to spread because too few people are willing to be vaccinated. "It is so hard to talk people into taking flu shots," he said. "People refuse, even if the healthcare workers knock on their doors and offered free vaccine."

"Many people simply don't bother to get vaccinated because they don't take flu seriously," said Shu.

Meanwhile, others fear potential adverse reactions.

In 2009, around 800 children, mainly in Sweden but also in other parts of Europe, developed narcolepsy, a neurological disorder, after being vaccinated with the Pandemrix H1N1 swine flu vaccine made by the drugmaker GlaxoSmithKline, according to reports by Reuters.

"So far, a link between the two cannot be substantiated and that shouldn't prevent people from taking the flu shot for proven protection," He noted.

Under the nation's vaccination programs, people have to pay for flu shots.

"A free nationwide service would help boost the coverage quite a lot," He said.

In 2007 in Beijing, the local government began a program to vaccinate students and the elderly free of charge every year.

Since then, an average 1.7 million from those groups in the capital have received the shot during the flu season, said He.

The figure before that fluctuated quite a lot, from 1 million to 1.8 million, "which affected a sustainable flu intervention effort on the whole", he said, stressing "the money is worth paying."

Every yuan the government spends on vaccination may help save 10 yuan ($1.60) in flu-related medical expenditure, said He, citing a study conducted in 2008. The first groups to receive the shots should include children aged between 6 months and 5 years, people aged 60 and older, sufferers of chronic diseases, pregnant women, medical and kindergarten workers, according to the China CDC's recommendations.

These groups totaled 570 million on the Chinese mainland, around 43 percent of the population, according to Feng Luzhao, a researcher with the China CDC's infectious disease prevention and control department.

A 2009 survey conducted by the China CDC showed vaccination coverage in areas of relative wealth is higher than in underprivileged regions.

Overreaction?

Sniffling, groggy and frightened, Zhao Yanwei had flu. The 28-year-old Beijing resident dragged himself to the China-Japan Friendship Hospital but found the fever clinic was packed with patients, coughing and wheezing.

Zhao had been running a temperature as high as 39C for two days, but the medicine he bought from a pharmacy hadn't worked. "I have never thought of getting vaccinated," said Zhao, who wore a protective mask. "I would have got the shot if I had known the flu would bring so much pain."

Yu Xin, who also had flu-like symptoms, said he hadn't had the shot and had no intention of doing so.

"Don't you think people overreact to a cold?" he asked. "Besides, it needs to be done every year. How do you know the vaccine is safe and won't cause any side effects?"

Contact the writers at shanjuan@chinadaily.com.cn and pengyining@chinadaily.com.cn