Five surprising moments in vaccine history

When I set out to make a video series about vaccines, I didn't know just how much history I would uncover. I figured this would be a straightforward science story that answered some of the big questions that worry parents.

Questions such as, "Why is there aluminum in vaccines?" and "Is it dangerous to give my kid so many shots at one time?"

Vaccines, however, have been around for over 200 years. And to understand the importance of vaccines and how they're made, it helps to know a bit about that history, reports The Washington Post.

Here are some of the most surprising things I learned.

1. Before vaccines, there was another way to immunise yourself, called "variolation." Variolation was a way to protect yourself from a terrible disease called smallpox, which could be fatal. If it didn't kill you, it could leave intensive, disfiguring scarring.

There were a few ways to variolate a person, but a common one was to dip a thread in a sick person's smallpox pustule, and run it through a small incision in an uninfected person's skin. Another was to blow dried scabs up a person's nose.

2. Variolation was brought to the United States by an enslaved man named Onesimus. Little is known about him, except that he was owned by Cotton Mather, the Puritan minister known for his involvement in the Salem witch trials.

Variolation had a champion in George Washington. He actually required his troops to be variolated during the Revolutionary War. Washington had suffered through a case of smallpox and was concerned the British would use the disease as a biological weapon.

3. The anti-vaccination movement is way older than I thought. The first true vaccine (again, for smallpox) was created in the late 1700s. That was before people understood germ theory - the idea that bacteria and viruses cause disease. It's no wonder that vaccine skepticism followed right away. However, smallpox was so terrifying that, for the most part, people adopted the vaccine, both in the United States and Europe.

4. Early vaccines were very crude. Sometimes, doctors would store smallpox vaccination scabs in little wax-filled lockets, and use the scab to inoculate new patients. It was pretty simple (and a little gross), but it worked.

5. The last smallpox epidemic in the United States was in New York City in the 1940s. It was brought to the city by a man from Maine who contracted it while vacationing in Mexico. By the time he got to New York, he was feeling ill, but still checked into a hotel and took his wife shopping. Soon after, he went to a hospital, where he died of his infection.

Within a few weeks, other people came down with the virus. In response, New Yorkers lined up to get the vaccine, and in the end, around 2 million people were vaccinated. (I include a photograph of the vaccination lines in episode 1 of the series, and it is truly remarkable.)

That's just a small sampling of what I learned.

Vaccines actually changed dramatically in the late 1800s. Once germ theory was understood, scientists started making vaccines in the lab, for terrifying diseases such as diphtheria and polio.