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 1900s there were three flu pandemics, including the Spanish Flu of 1918 which caused over 40 million deaths worldwide (over 500,000 in the U.S.)

The Epidemic of Influenza in Connecticut

According to the Centers for Disease Control and Prevention (CDC), during the H1N1 influenza pandemic in 2009 more than 60 million people got sick, more than 274,000 were hospitalized, and more than 12,000 died in the U.S. No one knows for sure when, or where, the next flu pandemic might happen, but everyone should be prepared.

How does a flu pandemic start?

Flu viruses are constantly changing, producing new strains. Influenza pandemics occur when a virus emerges that is so different from previous strains that few, if any, people have any immunity to it. This allows it to spread widely and rapidly, potentially affecting millions of people worldwide. The new virus may be the result of an animal virus, usually from a bird, mixing with a human virus to produce a new strain.

What is the difference between pandemic flu and ordinary flu?

Ordinary Flu
  • Occurs every year during the winter
  • Affects up to about 10% of the population
  • For most people it is an unpleasant, but not life-threatening, infection
  • The very young, the very old, and people with certain chronic illnesses are most at risk of serious illness
  • Annual vaccination is available
  • Antiviral drugs are available to treat those at special risk
Pandemic Flu
  • Has occurred four times in the last 100 years
  • Can occur at any time of the year
  • Is a more serious infection for everyone
  • People of every age may be at risk of serious illness
  • A vaccine probably won’t be available when the pandemic starts – when it does become available the aim will be to immunize people as rapidly as possible as vaccine supplies become available
  • Antiviral drugs are likely to be in limited supply and will have to be used to best effect according to how the disease develops
Vaccine against ordinary flu will not protect against pandemic flu. However, getting your annual flu shot is one of several things you can do to keep yourself healthy, and that may help you fight off the pandemic virus.


How likely is a flu pandemic? 

Four pandemics have occurred in the last 100 years, in 1918, 1957, 1968 and 2009. Scientists predict that another pandemic will happen, although they cannot say exactly when.


How likely is it that pandemic flu will spread to the U.S.?

The World Health Organization, CDC, and the Connecticut Department of Public Health are watching for the first signs of an emerging pandemic.Connecticut is working with many different collaborators and partners to prepare for a possible pandemic.
In 1918, pandemic influenza spread across the country in less than a month. Now, in the era of international air travel, a pandemic will probably spread even faster. As a result:
  • Many people will get sick with the flu
  • There will be a huge demand for health services
  • Many aspects of daily life will be disrupted
  • There will be many deaths

How likely am I to catch pandemic flu?


You are more likely to catch it than ordinary flu because it spreads rapidly and very few people will have any immunity to it. Everyone will be at risk. Some groups of people may be more at risk than others, but every pandemic is different, so until the virus starts spreading it is very difficult to predict who these groups might be. With ordinary flu the groups of people more likely to become seriously ill include:
  • The very young
  • People over 65 years of age
  • People with existing medical conditions such as lung diseases, diabetes, cancer, kidney, or heart problems
  • People who have immune system problems because of certain medical treatments, or illnesses like HIV/AIDS

The groups most likely to become ill will probably be different during a pandemic.


How will I know if pandemic flu has reached the U.S.?

The World Health Organization has an international system in place for tracking the emergence of a new pandemic. CDC, the U.S. Department of Health and Human Services (DHHS), and the Connecticut Department of Public Health will also be monitoring the situation.
If it looks like a pandemic is going to reach the U.S. government will issue warnings and work with the media to advise people on the best course of action. If it looks likely that a pandemic will reach Connecticut, health officials will use the media and this website to advise people on what they should do.



For more information about being prepared for pandemic Flu or other emergency follow CTDPH on social media.

You can also request a free copy of the CT Guide to Emergency Preparedness  by calling 860-509-7599