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Home › Topics › Infectious Diseases › Infections A-Z › Pandemic Influenza › General information ›Frequently asked questions on pandemic influenza ›  About the virus
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About the virus

What is the difference between pandemic flu and seasonal flu?

What are the differences between low pathogenic and highly pathogenic avian influenza viruses?

 

How can a normal flu virus become a pandemic flu virus?

There are a number of key characteristics that experts look for when deciding whether or not a flu virus is a potentially pandemic strain. For an influenza virus to be capable of causing a pandemic, it must be able to: infect people (not just other mammals and birds); cause illness in a high proportion of those infected; spread easily from human-to-human, and spread widely. These features will mainly be because the virus is significantly different from previously circulating strains and most people will have little or no immunity to it. All previous flu pandemics exhibited these characteristics.

What is the difference between pandemic flu and seasonal flu?

Flu pandemics are global epidemics of a newly emerged strain of flu to which most people have little or no immunity. Pandemic flu differs from seasonal flu in important ways. Seasonal flu occurs seasonally (typically in the winter months between December and March in the Northern Hemisphere) allowing time to identify the virus and administer a vaccine in advance, whereas pandemic flu can occur at any time of the year allowing no time for a vaccine to be prepared because the virus is completely new. Seasonal flu most seriously affects the elderly and vulnerable groups while pandemic flu can affect people of any age. The symptoms of pandemic flu are similar to seasonal flu. However, in the case of pandemic flu, these symptoms are likely to be worse, resulting in more severe illness and possibly death.

What are the differences between low pathogenic and highly pathogenic avian influenza viruses?

The terms low or highly pathogenic avian influenza refers to the potential for these viruses to kill poultry. It does not refer to how serious the viruses may be to humans.


Last reviewed: 13 August 2008