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1918 Pandemic Flu and the Flu Vaccine (P.S. get your flu shot)

Updated: Nov 29, 2021

Flu season occurs between late November and early March every year. Flu spreads through droplets when people sneeze or cough and on surfaces. People are contagious one day before symptoms appear and up to a week after. Flu symptoms include fever, headache, fatigue (feeling tired), dry cough, sore throat, stuffy nose, nausea (upset stomach). It is best to stay home and take care of yourself when you do not feel well and only go back to school or work at least 24 hours after a fever is gone.


People younger than age 5 and over age 65 are at greater risk for dying from the flu. Everyone older than 6 months should get a flu vaccine every year. If you do not like needles, you can ask your doctor about a nasal (through the nose) flu spray. Vaccines do not give people the flu.


Ways to Stay Healthy:

  • Avoid being around sick people if possible

  • Wash your hands frequently with soap and water, or use hand sanitizer

  • Cover your mouth when coughing or sneezing with the inside of your arm rather than your hand

  • Avoid touching your face

  • Disinfect surfaces that may be contaminated

In 1918 about 50 million people (or 3%) of the world’s population died from a pandemic influenza. A pandemic influenza is a flu that spreads across the world, same as COVID-19 has spread across the world. This is a low estimate since there were no systems to track deaths the way we are able to do today (like how we track COVID-19 deaths). This was not the first time a flu crossed the world, but it was the worst.

This pandemic flu is also called the Spanish flu, even though none of the flu strains started in Spain. Since Spain was neutral (not part of any of the conflict) in World War I and the Spanish press (newspapers and news reporters) was able to publish information about the spread of the disease, the first news about the pandemic came from Spanish sources. There are many hypotheses (educated guesses that can be tested and used to guide further studies) about where this strain of influenza began. It might have begun in the Midwest United States, where there were widespread cases of influenza in pig livestock, but no one knows for sure.


At first there were no treatments for this flu. By the end of the pandemic, blood transfusions from survivors were used, but matching the patient to blood typing was difficult and not always able to be done.

Scientists thought the influenza was caused by a bacterium (plural: bacteria, a type of germ and the smallest of all living organisms) They could see the bacterium (now known as Haemophilus influenzae, or H. influenza) under a microscope but also knew that there were parts of the disease (called agents) that were smaller than bacteria. Not being able to view these agents, they debated (argued and discussed) about whether they were chemicals or very small organisms. Vaccines against these very small agents, which they called viruses, had already been made going back to the smallpox vaccine in the late 1700s.

In 1931 an American virologist (someone who studies viruses) named Richard Shope studied pigs carrying swine flu and used the same procedures that had been used to study the causes of yellow fever and other diseases. He found that H. influenza made swine flu worse but did not cause it. In 1936 Shope discovered that people living and working on the pig farms had antibodies to the swine flu, showing that human and swine disease were related. Antibodies are special proteins that recognize foreign materials and help the body get rid of them.


Also in 1931 researchers at Vanderbilt University found ways to grow the influenza virus in fertile chicken eggs (eggs that are able to produce offspring). This meant that they no longer had to get the virus from sick people or animals. By growing their own viruses and comparing the responses in lab animals, scientists found two types of flu viruses and named them A and B. The 1918 pandemic virus was a Type A virus. Today we know that Type A viruses are more dangerous because they infect both humans and some other animals. Type B viruses are in humans only.


Researchers began working on a vaccine and learned that immunity against one type of virus does not give immunity against another. British researchers tested a vaccine on soldiers in 1937 to prepare for another war. The U.S. Army began tests of vaccines in 1938. The first flu vaccine for U.S. soldiers came in 1944 and for everyone else in 1945.


Other discoveries came from the search for the flu virus and the flu vaccine:

  • It created tools to make other vaccines.

  • We still use fertile eggs to grow viruses.

  • It led to our understanding of genes and the chemicals produced by them.

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