1945Flu (influenza)

History of flu (influenza): Outbreaks and vaccine timeline

Learn about flu pandemics, the flu (influenza) vaccine and its impact.

Nurse wearing a mask assists a patient laying in a bed in a hospital

Nurse assisting patient with the flu

A nurse assists a patient at the Walter Reed Hospital flu ward during the flu pandemic of 1918 and 2019.


A flu (influenza) pandemic occurs. The flu pandemic is caused by a new H1N1 flu strain. In New York, people with the flu are required to be isolated at home. In Chicago, movie theaters and theaters close and public gatherings are not allowed. In San Francisco, people who work for the public must wear masks and others are encouraged to wear masks as well. The American Public Health Association suggests that people avoid public transportation. In southeastern Minnesota, near Mayo Clinic, many public spaces such as theaters, churches, meeting places and some schools are closed.

The flu pandemic lasts from 1918 to 1920. From spring of 1918 to spring of 1919, the flu causes more than 550,000 deaths in the U.S. and more than 20 million deaths worldwide.

In the fall of 1918 at Mayo Clinic, people with the flu and other contagious illnesses are cared for in the isolation hospital. Keeping patients with these illnesses isolated and keeping high standards of cleanliness likely prevented infections and saved lives. The isolation hospital of 40 beds is soon filled. The hospital is short of medical staff, and everyone on staff must help where needed. For example, nurses sometimes help in the kitchen and the laundry.

Mayo Clinic’s Dr. Edward C. Rosenow invents a flu serum that is made up of a mixed vaccine that includes bacteria that cause pneumonia. Dr. Rosenow gives the serum to Rochester residents for free. While Dr. Rosenow doesn’t state that the serum works in protecting against the flu, he notes that the serum doesn’t cause harm and might help provide some protection. Mayo Clinic receives many requests for the serum, which is sent to people across Minnesota and the Midwest. In the end, the serum doesn’t work as a vaccine to protect against the flu. But it might have helped protect people against pneumonia after having the flu.

Army men in a line wearing masks at a hospital during the flu pandemic of 1918 and 1919

Army men wearing masks

Army men stand in a line wearing masks at a U.S. Army hospital during the flu pandemic of 1918 and 1919.

1930s and 1940s

Researchers study flu viruses and develop flu vaccines. At first, mainly military members can get flu vaccines.


The first flu vaccines are approved for use for people who aren’t in the U.S. military.


A new H2N2 flu strain causes another flu pandemic. About 116,000 people die in the U.S. and about 1.1. million die worldwide.


In response to the flu pandemic that happened from 1957 to 1958, the U.S. Public Health Service recommends flu vaccines for people in the U.S. who are at high risk of flu complications.


A new H3N2 flu strain causes another flu pandemic. This flu pandemic causes about 100,000 deaths in the U.S. and about 1 million deaths throughout the world. Researchers develop flu vaccines for the specific flu strains causing the pandemic.


At Fort Dix, a flu outbreak caused by the H1N1 flu strain leads to the development of a flu vaccination program aimed at preventing flu pandemics.


Bird flu (avian influenza) caused by the H5N1 flu strain infects people. This leads to the development of pandemic flu response plans in the U.S. and throughout the world.


ACIP recommends that children ages 6 to 23 months old get an annual flu vaccine.


The FDA approves a flu vaccine for avian influenza A caused by the H5N1 flu strain.


ACIP recommends that people ages 6 months to 18 years old get an annual flu vaccine.


A new H1N1 flu strain causes a flu pandemic. During 2009, the flu causes about 61 million illnesses, 274,0000 hospital stays and 12,400 deaths. Later in 2009, an H1N1 flu vaccine becomes available.

During the H1N1 flu pandemic, Mayo Clinic staff are trained in infection control and prevention. A disaster preparedness team meets regularly to discuss flu planning with clinical areas. Mayo Clinic gives recommendations about H1N1 precautions and provides education about how H1N1 spreads to employees and the community.


ACIP recommends that everyone age 6 months and older get an annual flu vaccine. Gregory Poland, M.D., head of the Vaccine Research Group at Mayo Clinic, introduces and makes this recommendation. Dr. Poland will also recommend that health care providers be required to get vaccinated against the flu in 2016.


Flu vaccines prevent about 7.5 million illnesses, 3.7 million doctor visits, 105,000 hospital stays and 6,300 deaths.

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