More than 54 percent of Chinese people do not plan to receive the A/H1N1 flu vaccine because they doubt its safety and quality, according to a new survey by China Daily and major portal Sohu.com.

The initial results from 2,000 respondents stand in significant contrast with a survey conducted by Sohu.com two months ago in which 76 percent of 2,000 said they want the inoculation. It also marks the first time that more than half of a poll's respondents have shown a lack of trust in the vaccine.

"The vaccine has been developed and administered so quickly that I couldn't help questioning its quality and reliability," said Zhang Lin, a 36-year-old working mom in Beijing, who refused free vaccination for her 8-year-old boy.

Currently the inoculation program is being scaled up nationwide and would cover 5 percent of the population by the end of the year, said Health Minister Chen Zhu. The intensified effort comes as the outbreak is expected to peak around December in most areas of the nation.

"Tens of millions could be infected," warned Zeng Guang, chief epidemiologist at the Chinese Center for Disease Control and Prevention (CDC).

"A surge of critical cases or even deaths would be unavoidable," said He Xiong, deputy director of the Beijing CDC.

But like Zhang, the 36-year-old mother, many are casting doubt on the vaccine.

Nearly 70 percent of those who did not want the vaccine in the survey said they didn't trust its quality and safety; 23 of those who didn't want it said they feared potential adverse reactions.

About 11 percent of the 2,000 respondents said they were young and healthy and didn't need the vaccine.

Scientists, however, said these concerns were not well grounded particularly when the number of infections, which stood at 33,064 on the Chinese mainland by Friday, have increased rapidly with more severe cases emerging and four H1N1-related deaths reported within this month.

The latest death in China involved a 7-year-old boy in Heilongjiang province who died of seasonal influenza and severe pneumonia on Friday, said local health authorities. The H1N1 strain was found in the flu virus that infected the first grader.

Starting from late September, China has so far inoculated more than 300,000 people, mainly young students and old people against H1N1, with 150 showing mild adverse reactions like swelling and fever.

Worldwide, nearly 5,000 people have reportedly died from the H1N1 flu, according to the World Health Organization (WHO). US President Barack Obama also declared on Friday the H1N1 outbreak a national emergency.

The illness, unlike other flu strains, has been particularly tough on children and young adults and everyone is susceptible, experts said.

A recent New England Journal of Medicine study showed that among Americans hospitalized with A/H1N1 flu last spring, one in four ended up in intensive care and 7 percent of them died.

WHO spokesman Gregory Hartl said the H1N1 vaccine had been used in seasonal flu shot formulation. He said the seasonal flu shot had been among the safest vaccines known to exist.

"The most important tool we have to fight this pandemic is the vaccine. Bad reactions are fully to be expected, especially the mild types though," he stressed.

Besides, the speed with which China has brought a vaccine to market is not surprising, said Yuen Kwok-yung, head of the Department of Microbiology at the University of Hong Kong.

"Making flu vaccines is not that technically demanding," he explained.

He indicated there might be more H1N1-related fatalities in China than reported. "Deaths from preexisting conditions and other complications from the virus were not counted here."