Influenza is not going anywhere, anytime soon. While we’ve been able to eradicate the measles, smallpox and the Black Plague, flu pandemics continue to occur over and over again throughout history. In fact, since 1918, there have been four major flu pandemics, each with completely different characteristics. The good news is that while the flu once decimated entire populations, these days it can be somewhat controlled with vaccines.
The Spanish Flu (1918-1919)
Illness from the 1918 flu pandemic was swift and deadly. People could be perfectly healthy in the morning, and by that night, dead. Those who caught the Spanish Flu didn’t usually die from the flu itself but from complications caused by the bacteria associated with it.
During the 1918 pandemic, 20-40% of the world’s population caught the flu. An estimated 50 million people died; 675,000 of those were Americans.
Unlike earlier flu outbreaks, the 1918 Spanish Flu saw high illness and mortality rates among healthy adults; those rates were highest among adults 20- to 50-years-old.
1957 – 1958
In 1957, a new flu virus was identified in the Far East. Immunity to the strain was rare in people younger than 65-years-old. Health officials closely monitored this flu outbreak, and a vaccine was available in limited supply by August 1957.
In the summer of 1957, the virus came to the United States. By autumn, children returned to the classroom, spread the flu amongst one another and brought it home to their families. Infection rates peaked among school children, young adults and pregnant women in October of that year.
In January and February of 1958, a new wave of the flu surfaced. Most influenza-related deaths occurred between September 1957 and March 1958. Nearly 70,000 people in the United States died from the flu that year.
1968 – 1969
In 1968, a new flu virus was detected in Hong Kong. It came to the United States in September 1968, but deaths from the illness didn’t peak until December. The number of fatalities between September 1968 and March 1969 was 33,800.
Swine Flu (2009 – 2010)
In spring of 2009, the H1N1 virus spread quickly across the United States. The first U.S. case of swine flu was diagnosed on April 15, 2009. By April 21, the CDC was working on a vaccine. Five days later, the government declared H1N1 a public health emergency.
Seventy-four countries were affected by the swine flu pandemic. The vaccine supply was very limited, so only those with the highest risk of complications received it at first.
By November 2009, 48 states had reported cases of H1N1. As immunization became widespread, 80 million people were vaccinated against the flu. The CDC estimates that 43-89 million people had H1N1 that year and that there were between 8,870 and 18,300 H1N1 related deaths.
The flu is linked to between 3,000 and 49,000 deaths and 200,000 hospitalizations each year in the United States. As of today, some 440 Chinese people have been infected and 122 died from a new strain of influenza: H7N9. Another common avian flu is the H5N1 strain.
The viruses that cause the flu will continue to evolve as long as they find hospitable hosts to live in.