How are flu strains selected for annual flu vaccines? There have been four flu pandemics in the past 100 years. For a pandemic to occur, the new virus has to be able to infect people easily and spread efficiently from person to person. Influenza A also has pandemic potential, meaning that new (novel) influenza A viruses can emerge and cause a pandemic, defined as a global outbreak.
Influenza A and B viruses affect people and cause what is commonly referred to as “seasonal flu”, which occurs every year. What’s the difference between “seasonal flu” and “pandemic flu”? Antigenic shift refers to an abrupt, major change in an influenza A virus, resulting in new surface proteins that can infect humans.įlu viruses are constantly changing, which is why flu vaccine composition changes every year to match the circulating strains. Antigenic drift refers to small changes in the genetic make-up of flu viruses that can lead to changes in the surface proteins (hemagglutinin and neuraminidase). Flu viruses can change slightly (know as “antigenic drift”) or rapidly (known as “antigenic shift”). Influenza D: This type of flu primarily affects cattle and is not known to affect people.įlu viruses are constantly changing, which is why flu vaccine composition changes every year to match the circulating strains. Influenza C infections are not thought to cause human flu epidemics, which are defined as widespread flu illness in a localized area. Influenza C:This type of flu can affect people, but most often only causes mild illness. The two main categories (lineages) of influenza B include B/Yamagata and B/Victoria. Influenza B: These viruses only affect people and are characterized according to where the virus was originally isolated. Examples of flu viruses in this category include H1N1 and H3N2. There are 18 different H subtypes and 11 different N subtypes, and 131 subtype combinations have been detected in nature. These viruses are further separated into subtypes by number. These viruses are characterized by surface proteins, including hemagglutinin (“H”) and neuraminidase (“N”). Influenza A: Influenza A viruses can be found in many different animals, including birds and mammals, as well as humans. But there are actually four different types of flu viruses, including A, B, C, and D. To learn more about how and for what purposes Amazon uses personal information (such as Amazon Store order history), please visit our Privacy Notice.Some people may think influenza (flu) is just a standard virus that comes around every year. You can change your choices at any time by visiting Cookie Preferences, as described in the Cookie Notice. Click ‘Customise Cookies’ to decline these cookies, make more detailed choices, or learn more. Third parties use cookies for their purposes of displaying and measuring personalised ads, generating audience insights, and developing and improving products. This includes using first- and third-party cookies, which store or access standard device information such as a unique identifier. If you agree, we’ll also use cookies to complement your shopping experience across the Amazon stores as described in our Cookie Notice. We also use these cookies to understand how customers use our services (for example, by measuring site visits) so we can make improvements. We use cookies and similar tools that are necessary to enable you to make purchases, to enhance your shopping experiences and to provide our services, as detailed in our Cookie Notice.
0 kommentar(er)
