Influenza A Virus/ Influenza B Virus

According to the antigenic differences between NP and M genes, influenza viruses can be divided into four types: influenza A virus (IFV A), influenza B virus (IFV B), influenza C virus (IFV C) and influenza D virus (IFV D) [1]. For influenza A virus, it has many hosts and complex serotypes and can spread across hosts through genetic recombination and adaptive mutations. Humans lack lasting immunity to influenza A virus, so people of all ages are generally susceptible. Influenza A virus is the most major pathogens causing influenza pandemics [2]. For influenza B virus, it mostly spreads in small areas and currently has no subtypes. The human infections are mainly caused by influenza viruses of B/Yamagata or B/Victoria lineages. Among the monthly confirmed cases of influenza in 15 countries of the Asia-Pacific region, the diagnosis rate of influenza B virus ranges from 0 to 92% [3]. Unlike the influenza A virus, certain groups of people, such as children and the elderly, are susceptible to influenza B virus, which can easily cause complications, posing even more burdens to society than influenza A virus[4]. A negative result does not rule out IFV A/B infection and should not be used as the sole basis for diagnosis, treatment, or other management decisions. A positive result does not rule out bacterial infection or other viral co-infection outside IFV A/B virus.