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We Heard the Bells: Viewer's Guide

About the Program

Throughout history, influenza viruses have mutated and caused pandemics or global epidemics. In 1918, an especially virulent influenza pandemic struck, killing many Americans. Where did the1918 influenza come from? And why was it so lethal? What can we learn from those who survived the 1918 pandemic? 

The pandemic lasted from March 1918 to June 1920, and spread to nearly every part of the world -- even to the Arctic and remote Pacific islands.  An estimated 500 million people, one third of the world's population (approximately 1.6 billion at the time), became infected.1

The pandemic of 1918-1919 occurred in three waves. The first wave had occurred when mild influenza erupted in the late spring and summer of 1918. The second wave occurred with an outbreak of severe influenza in the fall of 1918, and the final wave occurred in the spring of 1919.

It was caused by an unusually deadly influenza A virus strain of subtype H1N1.  The pandemic’s most striking feature was its unusually high death rate among healthy adults aged 15-34 years.  During normal seasonal flu outbreaks, severe complications and death are most common among the elderly and young children.

According to Anthony S. Fauci, M.D., Director of the National Institute of Allergy and Infectious Diseases (NAID), with the National Institutes of Health, "The 1918-1919 influenza pandemic was a defining event in the history of public health. The legacy of that pandemic lives on in many ways, including the fact that the descendents of the 1918 virus have continued to circulate for nine decades." 2 We Heard the Bells provides a unique glimpse into history through the personal stories shared by those who survived the flu pandemic of 1918.

About this Guide

What happened in 1918 when so many people became ill or died from influenza?  What is the difference between seasonal influenza and pandemic flu?  How can we protect ourselves from influenza?  What lessons can be learned from the 1918 flu?  The We Heard the Bells Viewer’s Guide explores these questions, while providing resources for finding current information about flu.

About the Flu

Flu refers to illnesses caused by a number of different influenza viruses.  These viruses are dynamic and continuously evolving.  Flu can cause a range of symptoms, and complications from the flu can be life-threatening.

There are three types of influenza viruses: A, B and C.

Human influenza A and B viruses cause seasonal epidemics of disease nearly every winter in the United States. Influenza type C infections cause a mild respiratory illness.

Influenza A viruses cause the most severe form of illness and are responsible for most large pandemics.  Influenza A viruses are divided into subtypes based on two proteins on the surface of the virus: the hemagglutinin (H) and the neuraminidase (N).  There are 16 different hemagglutinin subtypes and 9 different neuraminidase subtypes.

Influenza A viruses can be further broken down into different strains.  Current subtypes of influenza A viruses found in people are influenza A (H1N1) and influenza A (H3N2) viruses.  Influenza A viruses can mutate faster than influenza B viruses.   

Influenza B viruses are not divided into subtypes.  However, influenza B viruses can be broken down into different strains. Influenza B can cause illness and death in humans, but is not known for causing worldwide pandemics.  Influenza virus B is usually included in the annual seasonal flu shot developed by health authorities, along with two strains of influenza virus A.

Influenza C is the rarest and slowest evolving of the three species of influenza. It usually causes mild illness, though it can occasionally cause more severe flu.  Outbreaks are typically local and do not become large epidemics or global pandemics.

Annual outbreaks of the seasonal flu usually occur during the late fall through early spring.  Flu symptoms may include fever, coughing, sore throat, runny or stuffy nose, headaches, body aches, chills and fatigue.  Most healthy people recover from the flu without problems, but people with certain chronic conditions like diabetes, asthma, lung or heart disease are at risk for serious health complications from the flu.  In a typical year, approximately 5 to 20 percent of the U.S. population is infected with the seasonal flu and approximately 36,000 flu-related deaths are reported, primarily in persons over age 65.

What is Pandemic Influenza?

A pandemic is a global disease outbreak. Read about the history of pandemics. Influenza viruses are constantly evolving.  An influenza pandemic occurs when a new influenza A virus emerges for which there is little or no immunity in the human population; the virus causes serious illness and spreads easily from person-to-person worldwide.  

On June 11, 2009, the World Health Organization (WHO) declared that a global pandemic of H1N1 flu was underway.3   This H1N1 influenza is genetically similar to the deadly 1918-1919 flu.  However, unlike the early 1900s, there are now available tools like anti-viral medications, antibiotics to treat bacterial co-infections, and mechanical ventilators to help prevent deaths from severe pneumonia.

In reconstructing the 1918 influenza virus, researchers learned which genes were responsible for making the virus so harmful. This is an important advance for pandemic preparedness efforts because knowing which genes are responsible for causing severe illness can help scientists develop new drugs and vaccines.

Historically, the 20th century has seen three pandemics of influenza:

  • 1918 influenza pandemic caused at least 675,000 U.S. deaths and up to 50 million deaths worldwide.
  • 1957 influenza pandemic caused at least 70,000 U.S. deaths and 1 to 2 million deaths worldwide.
  • 1968 influenza pandemic caused about 34,000 U.S. deaths and 700,000 deaths worldwide.

In April 2009, the first cases of a novel H1N1 influenza strain were reported in California and Mexico.  In only seven months, H1N1 swept through nearly 200 countries, killing nearly 4,000 people. 

Another, highly lethal H5N1 flu is being closely tracked overseas in Asia, Africa, the Pacific, Europe and the Near East.  Rare human infections with the H5N1 flu virus have occurred, but it remains a serious concern with the potential to cause a deadly pandemic.

How Does Seasonal Flu Differ From Pandemic Flu?

A side-by-side chart detailing the differences between seasonal flu and pandemic flu. 

Symptoms of Flu

Details regarding flu symptoms, including how common Seasonal Flu symptoms compare with those of the 2009-2010 Pandemic Flu.  

Get medical care right away if the sick person at home:

  • has difficulty breathing, shortness of breath or fast breathing
  • has pain or pressure in the chest or abdomen
  • has purple or blue discoloration of the lips or skin
  • experiences severe or persistent vomiting
  • is unable to keep liquids down or has signs of dehydration such as dizziness when standing, absence of urination, or in infants, a lack of tears when they cry
  • has seizures
  • is less responsive than normal or becomes confused
  • has flu-like symptoms that seem to improve, but then return with fever and worse cough


Take these everyday steps to protect your health:

  • Get vaccinated. Vaccination is the best protection against flu.  Each year, the CDC makes recommendation as to certain priority groups that should be the first to receive influenza vaccination.  People who are at high-risk for flu and its complications (children, seniors, and people with certain health conditions) should also receive a pneumococcal vaccination.
  • Cover your nose and mouth with a tissue when you cough or sneeze. Throw the tissue in the trash after you use it. Influenza is thought to spread mainly person-to-person through the coughing or sneezing of infected people. This can happen when droplets from a cough or sneeze of an infected person are propelled through the air and deposited on the mouth or nose of people nearby.
  • Wash your hands often with soap and water, especially after you cough or sneeze. Alcohol-based hand cleaners are also effective.
  • Avoid touching your eyes, nose or mouth. Germs spread this way. Influenza viruses may also be spread when a person touches respiratory droplets on another person or an object and then touches his/her own mouth or nose (or someone else’s mouth or nose) before washing his/her hands.
  • Try to avoid close contact with sick people.
  • Stay home if you are sick until at least 24 hours after you no longer have a fever (100°F or 37.8°C) or signs of a fever (without the use of a fever-reducing medicine). With seasonal flu, people may be contagious from one day before they develop symptoms to up to 7 days after they get sick. Children, especially younger children, might be contagious for longer periods.
  • Follow public health advice regarding school closures, avoiding crowds and other social distancing measures. Stay informed.  Visit or call 1-800-CDC-INFO (1-800-232-4636) for more information.


Flu vaccine

The best way to prevent or lessen the severity of the flu is to get vaccinated.  Influenza vaccines are made from killed influenza virus or weakened versions of the live virus that will not lead to disease.  When vaccinated, the body’s immune system makes antibodies that will fight off infection if exposure to the virus occurs. 

There are two methods by which flu vaccines are administered:

  • The “flu shot,” which is given as an injection in the arm, is an inactivated (or killed) vaccine.  Because the viruses have been killed, the flu vaccine cannot give you the flu. 
  • The nasal flu spray vaccine, a spray taken in the nose, is a Live Attenuated Influenza Vaccine (LAIV).  “Attenuated” means that the virus in the vaccine preparation is weakened.

It takes about two weeks after vaccination for antibodies to develop in the body to provide protection against influenza virus infection.

The composition of the flu shot can change every year because the strains of influenza viruses that circulate in the environment can change from year-to-year.  Therefore it is important to be immunized against flu every year. 

Each year the Centers for Disease Control and Prevention (CDC) issues guidelines to health care professionals about groups of people who are at high risk for complications from flu and who should receive vaccination.  Generally, older people, young children and people with certain health conditions like asthma, diabetes and pregnancy are at high risk for serious flu complications.  During some flu seasons, the CDC may recommend that certain priority groups be the first to receive their vaccination.  Information about flu, vaccination and priority groups can be found on the Internet at

Children immunized for the first time may require more than one flu vaccination for full immunity.  Individuals who are allergic to eggs, or have ever had a serious allergic reaction should speak with their health care provider before getting vaccinated.  The viruses used for producing the vaccine are grown in chicken eggs.


Antivirals are prescription medications that can treat people who have already been infected by a virus.  They also can be used to prevent infection when given before or shortly after exposure to a virus and before illness occurs.  For example, if your loved one is diagnosed with the flu, an antiviral can help to protect you from catching this virus.

A key difference between a vaccine and antiviral drug is that the antiviral medicine will prevent infection only when administered within a certain time frame before or after exposure.  To be effective, antiviral medications must be used within the first 12 to 48 hours of onset of flu symptoms. 

A vaccine, on the other hand, can be given long before exposure to the virus and can provide protection over a long period of time. 


Antibiotics are medicines that kill bacteria and are, therefore, only useful for treating bacterial infections. The flu is a viral infection, not bacterial, and because of this it cannot be treated with antibiotics.  Inappropriate use of antibiotics contributes to the development of antibiotic resistance, which is a growing health concern. Some bacterial diseases that were once easily cured by antibiotics have become resistant to treatment.

Virus - A virus is a capsule of protein that contains genetic material. A virus cannot reproduce on its own; it must infect a living cell to grow.  The cold and the flu are both respiratory illnesses caused by different viruses. 

Bacteria - Bacteria are one-celled organisms that live on their own. They can multiply and reproduce by subdivision.  Influenza infections can make people more likely to develop bacterial pneumonia.  Pneumococcal infections are a serious complication of influenza and can cause death.  For this reason, people who are at high-risk for flu and its complications should also receive a pneumococcal vaccination.  If a person develops bacterial pneumonia as a result of having the flu, his or her doctor will likely prescribe an antibiotic to treat the pneumonia.

Over-the-Counter Treatments

Over-the-counter (OTC) treatments are medications you can get without a prescription from your doctor. They are usually household medicines, which commonly can be found at the pharmacy. People experiencing flu-like symptoms will commonly take OTC medications (such as pain and fever relievers and decongestants) to lessen the discomforts associated with fever, cough, aches and pains. Speak with a health care professional for information on using these and any other medications.

The following is a list of the common OTC medicines:

  • Analgesics relieve aches and pains, and reduce fever.
  • Antihistamines block histamines, which help dry a runny nose and watery eyes. They can cause drowsiness.
  • Expectorants work by thinning mucus so that it can more easily be coughed up.
  • Decongestants work by reducing nasal congestion.



    The U.S. Federal government’s source for current influenza information. includes up-to-date information for the general public, health care professionals, communities, schools, state and local governments and others.

    The official U.S. government site for people with Medicare. includes information on Medicare’s preventive services, benefits, health plans, prescription drug coverage, billing, appeals, and other Medicare information. 
  • Medicare Learning Network

    The official resource for national Medicare educational products designed for health care providers.   Developed by the Centers for Medicare & Medicaid Services (CMS), the Medicare Learning Network offers a product catalog, educational articles, fact sheets, Internet-based training courses, videos and other resources to provide health care professionals with the most current Medicare information. 
  • Centers for Disease Control and Prevention (CDC)

    The site provides health and safety information, including: diseases and conditions, emergency preparedness and response, environmental health, healthy living, national health statistics and other information.
  • National Association of City and County Health Officials (NACCHO)

    Use this site to find a local public health department and its contact information.  Local public health departments have information about vaccine requirements and locations where flu immunization can be obtained.
  • Pandemic Influenza Storybook

    Read the personal accounts from 1918 pandemic flu survivors, or post your own family story.  Site is hosted by the  Department of Health and Human Services.


1 Taubenberger JK, Morens DM.  1918 influenza: the mother of all pandemics.  Emerg Infect Dis [serial on the Internet]. 2006 Jan [cited on Jan. 3, 2010].  Available from

2 Oplinger AA.  Dynasty:  Influenza virus in 1918 and today.  National Institutes for Health press release.  June 29, 2009. [cited on January 3, 2010].  Available from

3 Chan, M. World now at start of 2009 influenza pandemic.  Statement to the press by Dr. Margaret Chan, Director-General of the World Health Organization.  June 11, 2009. [cited on January 3, 2010].  Available from


Antibiotic: A substance produced by bacteria or fungi that destroys or prevents the growth of other bacteria and fungi.

Antibody: A protein produced by the body's immune system in response to a foreign substance (antigen). Our bodies fight off an infection by producing antibodies.  

Antiviral: A drug that is used to prevent or treat a disease caused by a virus by interfering with the ability of the virus to multiply in number or spread from cell to cell.

CDC: Centers for Disease Control and Prevention, the U.S. government agency that focuses on public health efforts to prevent and control infectious and chronic diseases, injuries, workplace hazards, disabilities, and environmental health threats. CDC is one of 13 major operating components of the U.S. Department of Health and Human Services.

CMS: Centers for Medicare & Medicaid Services, the U.S. government agency which administers Medicare, Medicaid, and the Children’s Health Insurance Program.  Provides information for health professionals and regional governments, and serves 90 million beneficiaries.  CMS is one of 13 major operating components of the U.S. Department of Health and Human Services.

Contagious: A contagious disease is easily spread from one person to another by contact with the infectious agent that causes the disease. The agent may be in droplets of liquid particles made by coughing or sneezing, contaminated food utensils, water or food.

Immune system: The cells, tissues and organs that help the body to resist infection and disease by producing antibodies and/or altered cells that inhibit the multiplication of the infectious agent.

Influenza: A serious illness caused by a number of different influenza viruses that infect the respiratory tract.  Flu can cause a range of symptoms, including fever, chills and muscle aches. Each year in the U.S. on average more than 200,000 people are hospitalized from flu-related complications, and about 36,000 people die from flu-related causes.  

Pandemic flu is virulent human flu that causes a global outbreak, or pandemic, of serious illness. Because there is little natural immunity, the disease can spread easily from person to person.

Seasonal (or common) flu is a respiratory illness that can be transmitted person to person.  The flu season varies each year, but can run from September to March.  Most people have some immunity, and a vaccine is generally available.

Medicare:  A program administered by the Centers for Medicare & Medicaid Services (CMS) providing health insurance to people who are aged 65 and older, people under age 65 with certain disabilities, and people of all ages with End-Stage Renal Disease (permanent kidney failure requiring dialysis or a kidney transplant).

Mutation: Any alteration in a gene from its natural state. This change may be disease causing or a benign, normal variant.

Pandemic: The worldwide outbreak of a disease in humans in numbers clearly in excess of normal

Seasonal flu: A respiratory illness that can be transmitted from person to person.  Most people have some immunity, and a vaccine is produced annually.

Strain: A group of organisms within a species or variety.

Vaccine: A preparation consisting of antigens of a disease-causing organism which, when introduced into the body, stimulates the production of specific antibodies or altered cells. This produces an immune response to the disease-causing organism. The antigen in the preparation can be whole disease-causing organisms (killed or weakened) or parts of these organisms.

Virus: Any of various simple submicroscopic parasites of plants, animals and bacteria that often cause disease and that consists of genetic material. Viruses are unable to replicate without a host cell.