New Delhi, Oct 17 : China's National Health Commission has warned of a potential "twindemic" this winter and it stresses influenza prevention as flu activity in the southern provinces has increased since September with the flu season approaching and the remaining high risk of imported Covid-19 infections, Global Times reported. Autumn and winter are the two seasons with high incidence of respiratory infections such as influenza. The health commission released a notification to strengthen influenza prevention and control measures during the flu season which is combined with the risk of imported Covid-19 cases of new variants that will bring more uncertainties this winter. According to the health authority, influenza activity in the southern and northern provinces since March has been higher than the same period in 2020 and the influenza activity in the southern provinces has increased significantly since September. At present, the global Covid-19 pandemic remains at a high level, and the risk of imported cases continues to exist. The Covid-19 epidemic and the respiratory infectious diseases such as influenza can be combined and bring a potential "twindemic" during this upcoming winter and the next spring. Despite the overall prevalence of influenza staying relatively low during the last flu season, clusters of flu cases still occurred in schools, childcare institutions and other venues. The health authority urges the key institutions such as childcare institutions, schools and nursing homes to fulfill their responsibilities and strengthen efforts to detect, report and deal with cluster cases as early as possible. Besides, influenza vaccination will be promoted in an orderly manner among medical workers, large-scale activity attendees, staffers at nursing homes, childcare institutions and schools, as well as senior citizens, children and patients with chronic diseases. China Meteorological Administration on Friday issued the first "blue alert" of a cold spell which brought sudden temperature drops to vast areas across the country in East China, Central China and Northeast China over the weekend. Temperature in Beijing fell below zero Sunday morning, the lowest for the same period over the past 52 years. /IANS