Find a vaccination site near you at ct. What is Pandemic Flu? A flu pandemic happens when a new kind of flu virus causes people to get sick all over the world.
It can last for many months, affect many different places and be very dangerous. Millions of people around the world might get very sick. Many people could die. In the s there were three flu pandemics, including the Spanish Flu of which caused over 40 million deaths worldwide over , in the U.
The Epidemic of Influenza in Connecticut. According to the Centers for Disease Control and Prevention CDC , during the H1N1 influenza pandemic in more than 60 million people got sick, more than , were hospitalized, and more than 12, died in the U. Influenza A H3N2 viruses have formed many separate, genetically different clades in recent years that continue to co-circulate.
Similar to influenza A viruses, influenza B viruses can then be further classified into specific clades and sub-clades.
Influenza B viruses generally change more slowly in terms of their genetic and antigenic properties than influenza A viruses, especially influenza A H3N2 viruses. Influenza surveillance data from recent years shows co-circulation of influenza B viruses from both lineages in the United States and around the world.
However, the proportion of influenza B viruses from each lineage that circulate can vary by geographic location and by season. Figure 2 — This image shows how influenza viruses are named. The name starts with the virus type, followed by the place the virus was isolated, followed by the virus strain number often a sample identifier , the year isolated, and finally, the virus subtype.
CDC follows an internationally accepted naming convention for influenza viruses. This convention was accepted by WHO in and published in February in the Bulletin of the World Health Organization, 58 4 see A revision of the system of nomenclature for influenza viruses: a WHO Memorandum pdf icon[ KB, 7 pages]external icon pdf icon external icon.
The approach uses the following components:. Getting a flu vaccine can protect against these viruses as well as additional flu viruses that are antigenically similar to the viruses used to make the vaccine. Seasonal flu vaccines do not protect against influenza C or D viruses or against zoonotic animal-origin flu viruses that can cause human infections, such as variant or avian flu viruses.
In addition, flu vaccines will NOT protect against infection and illness caused by other viruses that also can cause influenza-like symptoms. There are many other viruses besides influenza that can result in influenza-like illness ILI that spread during flu season. To receive weekly email updates about Seasonal Flu, enter your email address:. When naming the influenza, researchers will look at the subtype of hemagglutinin and the subtype of neuraminidase on that particular virus.
There are 18 different subtypes of hemagglutinin and 11 different subtypes of neuraminidase, which means the there are a number of different ways the two proteins can be paired. Influenza B, the other type of virus that can have a serious effect on the human population, is classified by genetic lineage as opposed to subtype:.
So, for example, you may hear about an influenza B Victoria or B Yamagata virus. You don't hear about these designations on the news, but after subtypes and lineages, scientists further classify flu viruses into groups and subgroups, also called clades and subclades.
All of these classifications are important when it comes to how they impact you and what vaccines will or won't work against them. When you know how many different variations of the flu virus exist, and that new ones are mutating all the time, it's easier to understand why scientists have a tough time predicting the next big strain.
Three types of flu viruses—A, B, and C— cause seasonal influenza. Influenza D may also have the potential to do so if the potential for future transmission from animals to humans comes to fruition. Seasonal flu is the type of influenza that typically causes illness for just a few months out of the year. Flu season is different depending on where you are in the world. In the United States, it usually falls between October and April. Type A influenza is usually responsible for the majority of seasonal flu cases and typically causes the most severe cases.
It is found in humans and in animals. Influenza A is spread from person to person by people who are already infected. Touching objects the infected person has touched doorknobs, faucets, phones or even being in the same room as the person, especially if they are coughing or sneezing, is enough to become infected yourself. Based on the number of subtypes and strains, influenza A could theoretically have different combinations, but have been identified. These viruses are the ones you hear about that tend to mutate rapidly, which keeps scientists busy trying to predict their course and create the right vaccine to protect people from the next mutated form.
An influenza A infection may last for about one to two weeks. Type B flu is found primarily in humans. It has the potential to be very dangerous, but cases are typically less severe than with influenza A.
Influenza B viruses can cause epidemics but not pandemics spread of infection across large parts of the planet. Like the A virus, illness caused by influenza B may persist for a week or two. Type C flu, which affects only humans, is much milder than types A and B. It typically causes mild respiratory illnesses and it is not known to have caused any seasonal flu epidemics. Most people who contract influenza C will experience symptoms similar to those of a cold. Even so, influenza C can become serious in:.
In healthy people, influenza C usually goes away on its own in three to seven days. Influenza C outbreaks can sometimes co-exist with influenza A pandemics. In , influenza D virus was isolated from swine and cattle. It's been reported in multiple countries, suggesting worldwide distribution. To date, the influenza D virus has not demonstrated the ability to be passed from animals to humans, although scientists suggest that such a jump may be possible.
Meanwhile, influenza B viruses also affect humans and can be categorized by different strains and lineages. Influenza C viruses can cause mild respiratory illnesses but not epidemics, and modern flu vaccines do not protect against them. Finally, influenza D viruses primarily affect cattle and are not a problem for humans. The strains recommended for vaccination for the flu season in the northern hemisphere are:.
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