On our most recent episode of History Factory Plugged In, host Jason Dressel spoke with Robert Hicks, Ph.D., senior consulting scholar and William Maul Measey Chair for the History of Medicine at The College of Physicians of Philadelphia. For over a decade, he served as director of the Mütter Museum and Historical Medical Library at the college and has written extensively on the history of vaccinations.
Jason Dressel: So, Robert, what is the origin story of vaccines?
Dr. Robert Hicks: The origin of story of vaccines goes back thousands of years. The idea is that some material could be removed from the source of a smallpox-infected person’s raised sores, which release a liquid called lymph. Taking some of that lymph and scraping it into the skin of a healthy person would confer immunity to smallpox.
Now, there wasn’t any scientific understanding of the disease, but people put two and two together from observation. So that practice was active in many parts of the world hundreds of years ago. The difficulty is, you’re putting a deadly disease into a healthy person’s body, so there’s a risk they could get the full-blown disease. But in the late 1700s, we have vaccination, and it’s credited to a doctor—a country doctor in a country estate in the western parts of England, Edward Jenner.
Jenner noticed that milkmaids seemed to contract on their hands the same smallpox-looking sores as on the cow’s udders, but it would give them only mild symptoms of smallpox, and they would survive. He reasoned that if you could take that substance out of the cows’ pustules and inject it into a person, or scrape the skin and put it in, perhaps they’d be immune to the real target disease, smallpox. And that turned out to be true. Thus, vaccination was established, and the etymology of the word is from the words “cow pox.”
JD: Let’s talk about the last pandemic of 1918, known as the Spanish flu. Was there a vaccine developed for that virus? How did that global crisis from a century ago ultimately come to an end?
RH: The 1918 influenza pandemic we now know to be a strain of flu called H1N1. We know now, and they recognized then, that there could be multiple versions of the flu. Some seemed to hit harder than others, but even the weaker ones exhibited some of the same symptoms. You get sore throat, coughing, muscle aches, but you could get severe symptoms and have high mortality cases.
Although we know H1N1 was the 1918 flu and that H1N1 is what we all got vaccinated against for flu this flu season, we still do not know why it was such a high-mortality disease in 1918. But it came and it went swiftly. There may be waves of it that didn’t produce the huge number of deaths, but there was a huge spike in deaths in the United States around October and November of 1918.
Unlike COVID-19 today, doctors tracking the disease still did not understand what it was. It’s nature. They only knew it from observed symptoms. So, isolating it in a laboratory and figuring out how it behaves was not known in 1918. Nevertheless, there were some doctors who made some educated guesses. ‘Maybe we can get a vaccine.’ ‘Let’s try this.’ So, some vaccine was manufactured in limited quantities and tried on limited populations, and it apparently had no effect at all on the flu. It may have staved off some secondary infections that can creep in along with the flu, but it didn’t work against the flu.
But what happened in 1918 meant the research really began in earnest. And it wasn’t until the 1930s, long after the 1918-19 pandemic passed, that the flu virus was actually identified in the lab. And it wasn’t until years later, at the end of World War II, that the first effective vaccine was available. So, it was over 27 years from pandemic to an actual vaccine. In the meantime, someone had to figure out what the virus really was and how it behaved. There was no international coordinating body for research; every country was pretty much on its own—unlike now, where we have surveillance systems, a World Health Organization.
Nobody knows why the flu started to bump down. Herd immunity plays a role in this. But flu viruses can proliferate in multiple strains, and that’s one of the challenges of having a vaccine: You estimate what might be the target that’s going to really affect people and what isn’t. Since you mentioned Spanish flu, Spanish flu was another term for the flu of 1918, only because reports of its occurrence started to surface initially in Spain.
JD: Is the Spanish flu still around? Can you still contract it?
RH: Back in 1918, particularly with World War I going on, countries exercised a great deal of censorship and didn’t want to dampen the war effort by reporting about this disease coming up on the front lines. So, the flu virus that was the real killer is still out there. And we know that the flu pandemic in the 1950s and the swine flu pandemic of 2009, these didn’t have the mortality and sweep of COVID-19, but they nevertheless produced high numbers of deaths. And they all are genetically related to the 1918 flu. So that 1918 virus still lurks out there.
It’s still possible for flu variants to crop up and start killing people all over the place. There was a different strain, I think H5N1, that surfaced in China about four or five years ago and killed about one out of every two people. And it struck, and there was worry that something like that could take off in the way that COVID-19 has. Disease experts have been predicting for years that pandemics are coming and at least one in the next hundred years is likely to be a major flu. That prediction was made at an international conference just five years ago. And here we are today.