Historians believe that humans have been pounded by flu pandemics at various times for at least 400 years. But a flu pandemic is a rare event, taking place only 2 or 3 times a century.
On the other hand, every year we experience a seasonal flu epidemic. There's no question it's contagious, passing from person to person. But it certainly doesn't sweep across the planet the way a pandemic does.
In any one year in the United States, from 3,000 to 49,000 people die from complications of influenza, and about 200,000 people are hospitalized with flu-related complications. Most of these victims are very old or young, or have already weakened immune systems.
A pandemic, on the other hand, is fast and furious. It can sicken or kill normally healthy, working-age adults. Those who get better will take a long time to recover. Often, a second wave of sickness comes a few months after the first, claiming even more victims. A pandemic can have a serious impact on the economy and on social supports like the health care system.
Prominent pandemics of the 1900s
Last century, the world suffered through three separate pandemics:
- The Spanish flu in 1918-1919 was probably the worst pandemic on record. One or two out of every five people in the world got sick. The Spanish flu killed between 20 and 40 million people around the globe. For unknown reasons, most victims of this virus were in the prime of their lives.
- By the time the Asian flu first appeared in 1957-1958, modern medicine had advanced considerably. Scientists were able to identify the virus and, to a limited degree, produce a vaccine. Schools played a role in the quick spread of this disease. Most of the dead, though, were elderly.
- The Hong Kong flu hit in 1968-1969. This virus strain was most likely created when an animal became infected with a human flu and an avian flu at the same time. This was a relatively mild pandemic, killing a mere four million instead of 40 million.
Since 1969, the world's pandemic panic button has not been silent. We've had several scares. The swine flu in 1976 was at first thought to be similar to the powerful Spanish flu, raising alarms. The Russian flu in 1977 moved dangerously quickly through schoolchildren, but it was later found that many adults had already developed immunity.
The newest strain of pandemic influenza is the H1N1 flu virus, commonly known as the swine flu. It emerged in North America in April 2009. While the 2009 H1N1 virus seems to have virtually disappeared here in North America, largely due to an aggressive vaccination program initiated by the Canadian and US governments, it is expected to reappear during flu season along with other flu viruses. The 2010-2011 flu vaccine protects against 3 flu viruses including 2009 H1N1. H1N1 is still a concern in countries in the southern hemisphere, so travelers are encouraged to get vaccinated with the H1N1 flu shot if they are not already.
Today, the potential of avian flu to spark a pandemic continues to be a concern. Many experts are worried that modern air travel will allow a pandemic flu virus to literally fly around the world fast.
Lisa Bendall