There is no cross-immunity of different respiratory pathogens. It is suggested that high-risk people should be vaccinated with influenza vaccine as soon as possible.

　　CCTV News:At the press conference on January 14th, experts from China CDC introduced that the southern provinces of China have entered this influenza epidemic season since early October 2023 and the northern provinces since late October 2023. In the early stage, influenza A (H3N2) virus was the main epidemic strain. Recently, with the increase of the proportion of influenza B virus, the proportion of influenza B virus in some provinces exceeded that of influenza A virus. It is suggested that high-risk people should be vaccinated as soon as possible.

　　Wang Dayan, Director of National Influenza Center, Institute of Virology, China CDC:In the past three weeks, the proportion of influenza B virus in southern provinces continued to rise to 36.8%, and in the past five weeks, the proportion of influenza B virus in northern provinces continued to rise to 57.7%, and the proportion of influenza B virus in some provinces exceeded that of influenza A virus.

　　Influenza A and B viruses are distinguished by the sequence characteristics of their genes and proteins, and the seasonal influenza caused by them is difficult to distinguish in clinical symptoms. Distinguishing and identifying influenza A virus or influenza B virus depends on pathogen typing detection, such as nucleic acid detection and antigen detection. In the same influenza epidemic season, there are usually different types and subtypes of influenza viruses, but the proportion is different. The immune response after getting influenza A cannot provide immune protection for influenza B. In other words, even if you have had influenza A in this epidemic season, you may be infected with influenza B virus again.

　　At present, influenza vaccine contains influenza A (H1N1) subtype, influenza A (H3N2) subtype and influenza B. It is suggested that high-risk people should be vaccinated as early as possible every year.

　　Different respiratory pathogens have no cross-immunity.

　　In response to a reporter’s question, will there be repeated infection after getting respiratory diseases such as influenza A or B? Will repeated infection aggravate the condition? Relevant experts answered this question in detail at the press conference.

　　Wang Guiqiang, Director of Infectious Diseases Department of Peking University First Hospital:Winter is the season with frequent respiratory diseases, including influenza (influenza A, influenza B), Covid-19, respiratory syncytial virus, adenovirus and mycoplasma, etc. The immunity established by these pathogens is not lasting and can be repeatedly infected. These pathogens have no cross-protective immunity and can be infected simultaneously or alternately.

　　The same pathogen is repeatedly infected in a short time, and the disease is often milder because the immunity established by infection still exists. However, when different pathogens are infected at the same time, the disease may worsen, the respiratory immune barrier will be damaged after infection, and the risk of bacterial infection will increase, especially for the elderly, children and patients with basic diseases.

　　In the case of common respiratory infectious diseases, we suggest that everyone should do personal protection. If there are some symptoms of upper respiratory tract infection, differential diagnosis should be made in time.