While most researchers today are using cutting-edge technologies and methods to try to come up with a vaccine to protect against COVID-19, at least one group is looking to the past for clues. Scientists and historians working at McMaster University, the Mütter Museum in Philadelphia, and the University of Sydney have decoded the genome of old viruses that were used as smallpox vaccines by examining wartime vaccination kits.
A Cure Worse Than The Disease?
At the start of the Civil War, for every one death caused by combat, ten soldiers died from diseases including diarrhea, measles, and, most feared of all, smallpox. As the disease spread not only to soldiers but to other members of the population, it would eventually claim three in every ten lives before finally being eradicated by vaccination.
Before widespread acceptance and standardization of vaccination practices, though, the cure could, at times, be worse than the disease. Soldiers in the field knew that getting exposed to a small bit of the virus could help them from coming down with the full-blown disease, so they would cut themselves—often with unsanitary or rusty tools— and then break open a lesion on a fellow soldier and put the puss from the sore into their cut. It’s even reported that loved ones from home would mail smallpox scabs to soldiers for inoculation.
Milkmaids to the Rescue!
In some ways, this method caused more harm than good, as there was no telling what other diseases the smallpox-infected soldiers had, so instead of spreading the cure, the soldiers wound up spreading disease and more infection. This was even though English physician Edward Jenner had noticed in 1796 that milkmaids seemed mostly immune to smallpox, especially after they had gotten cowpox from the udders on the cows they were milking.
To test his theory that exposure to cowpox protected against smallpox, Jenner found a milkmaid who had an outbreak of cowpox, removed pus from a lesion, and put it in an incision on an eight-year-old boy. The boy got sick but recovered. Next, he exposed the same boy to smallpox and found that he was immune. While Jenner was on to something, it would take years for the inoculation method to catch on due to fear and suspicion, with the US among the last to get on board.
Fast Forward to 2020
The new research focused on taking samples from the vaccination kits that did manage to get made and used during the war, which are owned by the Mütter Museum. These kits typically consisted of lancets (small knives), glass plates for mixing infected fluids into vaccines, and tin boxes for collecting scabs. By using techniques developed at the McMaster Ancient DNA Centre to examine these items, the researchers were able to recreate the vaccine’s genome. The goal was to see how closely the germ strain used in the vaccine was related to the actual virus that caused smallpox as it’s a critical step in immunology to understand just how close the cure needs to be to the cause for it to be effective.
The analysis showed that the two viruses were, in fact, not very closely related at all. Still, the vaccine was entirely effective, leading to the eventual worldwide eradication of smallpox by 1980. They also discovered that during the 1860s and 1870s, vaccines were still being made using human subjects.
“Understanding the history, the evolution and the ways in which these viruses can function as vaccines is hugely important in contemporary times,” said evolutionary geneticist Hendrik Poinar, from the McMaster Ancient DNA Centre. “This work points to the importance of looking at the diversity of these vaccine strains found out in the wild. We don’t know how many could provide cross-protection from a wide range of viruses, such as flus or coronaviruses.”
The research has been published in the journal Genome Biology.