China has set up a national work group for immunization planning that will suggest ways to ensure vaccines are safe, the head of the Chinese Center for Disease Control and Prevention said on Monday.

The work group, led by a vice-minister of health, will analyze all incidents involving vaccine safety over the past few years to find the root sources of problems, Gao Fu, head of the center, said at a news conference. He didn't name the minister.

"Vaccines made in China are some of the best in the world," said Gao, who is also a member of China's top political advisory body. "We should have no doubt about the role of vaccines in disease prevention or the quality of vaccines made in China."

For example, he said, by promoting immunization, some infectious diseases that once seriously harmed people's health in China, such as smallpox, have been eliminated.

Hepatitis B once infected more than 10 percent of the population of China, but now only 0.3 percent of children under 5 years old are carriers because of mandatory immunization.

Gao made the comments in light of a series of incidents involving vaccine safety over the past few years.

In a major scandal last year, Changchun Changsheng Life Sciences, a vaccine producer in Changchun, Jilin province, faked production records and used expired material for the production of rabies vaccines over the past four years.

The company was ordered to suspend production, and senior executives were detained and face criminal charges. The company was ordered to pay fines of 9.1 billion yuan ($1.3 billion) for violations, one of the heaviest fines imposed on a pharmaceutical company over the past few years.

Following the revelations, top officials vowed harsh penalties and reform of the vaccine supervision system to eliminate loopholes. A new law on the management of vaccines was drafted for review.

Fang Laiying, former head of the Beijing Municipal Health Commission, said he has faith in the overall safety of drugs in China, but individual cases involving violations of the law can tarnish the image of the whole pharmaceutical sector.

"The government is intensifying its efforts in cases involving violations of drug safety laws, including severely punishing criminals and setting up strict accountability systems to improve supervision of the sector," he said.

Gao, the CDC head, said major infectious diseases such as dengue fever and AIDS will continue to be the priority in disease prevention and control this year.

"We will improve health education for the public, including promoting HIV prevention and providing more information to college students," he said. "We will also focus on some impoverished regions to help residents improve disease prevention to help them rise out of poverty."