What happens when a pandemic influenza virus emerges? If this new virus causes illness in infected people and can spread easily from person to person, an influenza pandemic can occur. For example, an exchange of genes between a human influenza A virus and an avian influenza A virus can create a new influenza A virus with a hemagglutinin protein or both a hemagglutinin protein and a neuraminidase protein from an avian influenza A virus. Antigenic shift also can happen when a non-human influenza A virus (for example an avian influenza virus) exchanges genetic information with other influenza A viruses in a process called genetic reassortment, and the resultant new virus is able to infect people. This can result from direct infection of humans with a non-human influenza A virus, such as a virus circulating among birds or pigs. Antigenic shift represents an abrupt, major change in an influenza A virus. Influenza viruses can change in two different ways, one of which is called “antigenic shift” and can result in the emergence of a new influenza virus. Theoretically, any combination of the 18 hemagglutinins and 11 neuraminidase proteins are possible, but not all have been found in animals and even fewer have been found to infect humans. There are 18 different hemagglutinin subtypes and 11 different neuraminidase subtypes (H1 through H18 and N1 through N11). Influenza A viruses are divided into subtypes based on two proteins on the surface of the virus: the hemagglutinin (H) and the neuraminidase (N). How do influenza A viruses change to cause a pandemic? Influenza A viruses are constantly changing, making it possible on very rare occasions for non-human influenza viruses to change in such a way that they can infect people easily and spread efficiently from person to person. Where do pandemic influenza viruses come from?ĭifferent animals-including birds and pigs-are hosts to influenza A viruses that do not normally infect people. Pandemics happen when new (novel) influenza A viruses emerge which are able to infect people easily and spread from person to person in an efficient and sustained way. Are there novel influenza A viruses that are of extra concern in terms of their pandemic threat?Īn influenza pandemic is a global outbreak of a new influenza A virus that is very different from current and recently circulating human seasonal influenza A viruses.How do you plan for the use of NPIs during a flu pandemic?.How would nonpharmaceutical interventions (NPIs) be used during a pandemic?.Are there other ways to slow a pandemic?.What treatments are available for pandemic flu?.How long would it take to develop a new pandemic vaccine?.Are there vaccines to protect against pandemic flu?.Will seasonal flu vaccines protect against pandemic flu?.What happens when a pandemic influenza virus emerges?.How do influenza A viruses change to cause a pandemic?.Where do pandemic influenza viruses come from?.
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