BEIJING -- China's health authorities have warned that the country has entered its respiratory illness season, but have said no unknown pathogens or newly emerged infectious diseases have been detected.

"All pathogens identified so far are known and common," said Wang Dayan, a researcher with the Chinese Center for Disease Control and Prevention, adding that influenza viruses, rhinoviruses and respiratory syncytial viruses are the main causes of acute respiratory infections this season.

According to Wang, flu activity nationwide remains moderate but continues to rise. The flu outbreak is expected to peak between mid-December and early January.

Southern provinces are seeing higher transmission than northern regions, with influenza A (H3N2) accounting for more than 95 percent of all reported cases, Wang said.

Jiao Zhenquan, an official with the National Administration of Disease Control and Prevention, said monitoring of acute respiratory infections has been in place to keep track of pathogen trends and viral mutations.

Health authorities are urging the public to get vaccinated against influenza and other preventable diseases while strengthening disease prevention awareness.

Local governments across the country are stepping up efforts to protect high-risk groups.

In Beijing, free flu vaccinations are being offered to the elderly and school-age children. In Tianjin, community health centers have launched pilot outpatient clinics for children's respiratory infections that integrate diagnosis and treatment, rapid testing, vaccination, health education, and referral services for severe cases.