False claim: the 1918 influenza pandemic was caused by vaccines

Shared 582 times as of March 31, 2020, a 2018 post ( here ) on a page called “Stop Mandatory Vaccination” claims that “the 1918 Influenza Epidemic was a Vaccine-caused Disease.” This claim is false.

The claim that the influenza pandemic of 1918 “was the after-effect of the massive nation-wide vaccine campaign” is unfounded. A vaccine against the flu did not exist at the time. According to the Centers for Disease Control and Prevention (CDC), having “no vaccine to protect against influenza infection and no antibiotics to treat secondary bacterial infections that can be associated with influenza infections” meant that “control efforts worldwide were limited to non-pharmaceutical interventions, such as isolation, quarantine, good personal hygiene, use of disinfectants, and limitations of public gatherings, which were applied unevenly.” ( here )

According to the CDC report “Achievements in Public Health, 1900-1999,” prior to 1900, the vaccines for smallpox, rabies, typhoid, cholera and plague had been developed in the U.S. (see Table 1 here ). The report states that “although the first vaccine against smallpox was developed in 1796, greater than 100 years later its use had not been widespread enough to fully control the disease… Four other vaccines -- against rabies, typhoid, cholera, and plague -- had been developed late in the 19th century but were not used widely by 1900.”

It is true that U.S. soldiers during World War I were subject to immunization requirements. However, it is not true, as the post claims, that this was the first major conflict in which this happened. Published by the National Institute of Health (NIH)’s National Center for Biotechnology Information (NCBI) in 2018, a paper ( here ) called “The US Military Commitment to Vaccine Development: A Century of Successes and Challenges,” says that “the first large-scale smallpox infection prevention campaign was conducted in 1777 by the Continental Army.”

In addition, a 2006 paper called “Immunization to Protect the US Armed Forces: Heritage, Current Practice, and Prospects,” published here by the Bloomberg School of Public Health at Johns Hopkins University, says that American servicemen underwent some version of smallpox immunization in the American Revolutionary War (1775-1783), the War of 1812, the Mexican-American War (1846-1848), the Civil War (1861-1865), and the Spanish-American War (1898). (See Table 2: “Immunizations used widely during major conflicts”) During World War I, soldiers were given live smallpox and whole cell typhoid inoculations, as well as therapeutic tetanus and diphtheria antitoxins. “With a vaccine to shield troops from typhoid bacteria during the unsanitary conditions of World War I,” the paper says, “a mere approximately 2,000 cases of typhoid fever, with 227 deaths, were reported among 4.1 million Americans in uniform.

Killing an estimated 675,000 Americans ( ), the 1918 H1N1 flu pandemic (also referred to as the “Spanish Influenza” or “Spanish flu”) was indeed the deadliest flu pandemic in modern history ( here ).

The outbreak of the “Spanish flu” was recorded in Spain in May 1918, several months before the November 11, 1918 armistice ending WWI. In the U.S., “it was first identified in military personnel in spring 1918” and that “crowded conditions and the movement of troops during World War I likely contributed to the spread of the 1918 virus around the world,” according to the CDC ( here , here ).

The specific origins of the “Spanish flu” outbreak are unknown, but it is known to have been an H1N1 Influenza “with genes of avian origins” ( here ). In terms of geography, “France, China and Britain have all been suggested as the potential birthplace of the virus, as has the United States” according to the history channel ( here ).

Finally, the claim that “more of our men were being killed by medical shots than by enemy shots from guns” is unsubstantiated. There is no evidence to show any vaccine killed more men than “enemy shots from guns”. According to a paper called “The U.S. Military and the Influenza Pandemic of 1918–1919,” by the NCBI in 2010, it was “influenza and pneumonia [that] killed more American soldiers and sailors during the war than did enemy weapons.” ( here ) The U.S. did not develop the first influenza vaccine until the 1940s ( here ) and the first pneumonia vaccine until 1977 ( here ).


False: the 1918 Spanish influenza pandemic was not caused by vaccines, WWI was not the first time that immunization was required for U.S. soldiers, more U.S. soldiers were killed by influenza and pneumonia, not “medical shots,” than by enemy fire during WWI.

This article was produced by the Reuters Fact Check team. Read more about our fact checking work here .