This winter's flu season could be particularly tough due to declining immunity among the world's population against the disease and lingering threats posed by the COVID-19 pandemic, public health experts said on Saturday.

Shen Hongbing, an academician with the Chinese Academy of Engineering and director of the Chinese Center for Disease Control and Prevention, said that after two years of low influenza activity amid the pandemic, pre-existing immunity against the disease has dropped.

This year, the world has already registered a marked increase in influenza incidence rates.

"With the 2022 autumn and winter seasons approaching and the northern hemisphere entering its flu season, the risk of seeing a rapid spread COVID-19 and other respiratory diseases, including flu, simultaneously is high," he said during the 2022 World Influenza Conference held online on Saturday and Sunday.

The conference was held jointly by the Chinese Preventive Medicine Association, Asia-Pacific Alliance for the Control of Influenza, Chinese Center for Disease Control and Prevention and Chinese Academy of Medical Sciences.

Shen said that coping with two contagious diseases at the same time will likely overstretch medical systems and heighten the death risk for vulnerable groups, such as the elderly and those with chronic diseases.

"As a result, it is of great significance to research how to improve surveillance, mass vaccination and disease control work during the COVID-19 pandemic," he said.

Feng Zijian, secretary-general of Chinese Preventive Medicine Association, suggested that people, especially those in vulnerable groups and workers at key venues, receive both flu and COVID-19 vaccines to protect themselves against both diseases.

He said that based on recommendations in the latest guideline on flu vaccination released by the Chinese CDC, people aged 18 and older can receive inactivated flu and inactivated COVID-19 vaccines at the same time, one on each arm, to save time and resources.

Shu Yuelong, president of the Asia-Pacific Alliance for the Control of Influenza, also warned against complacency against contagious illnesses and called for global cooperation in stepping up preparedness for the next pandemic.

Zhang Wenqing, director of the World Health Organization's Global Influenza program, said that an influenza pandemic is certain, highlighting the significance of implementing year-round surveillance of the flu.

In addition, she stressed that global coordination and collaboration is key for efficient respiratory virus surveillance.