The 98 people who had close contact with Shenzhen City´s first confirmed human bird flu patient were released after seven days of medical observation Tuesday.

None of the 98 had shown bird flu symptoms, said the municipal center for disease control and prevention (CDC) at a press conference on the same day.

"We have observed 98 people in Luohu and Longgang districts, including the patient´s family, colleagues, friends and medical staff from the Shenzhen People´s Hospital," said Jiang Lijuan, a spokeswoman of the center.

"All the 98 people had body contact with the bird flu patient after he showed symptoms and didn´t have any protection during the contact."

However, the CDC said a citywide second-level precautionary emergency system against bird flu, announced by authorities last week, was still in operation.

On June 11, a 31-year-old truck driver in Longgang District, known only by his surnamed Jiang, tested positive for H5N1 virus nucleic acid and was listed as a suspected human bird flu case by the CDC. He was later confirmed to be infected with bird flu by the Ministry of Health.

The CDC said Jiang had tested negative for H5N1 virus nucleic acid Saturday and is recovering from the disease.