Funtabulously Frivolous Friday Five 349

Not cowpox, as you’ve always been told. It is vaccinia.

BS you cry; everyone knows Edward Jenner, a silver-haired surgeon made the discovery in 1976. Through some dubious ethics, he noticed beautiful milkmaids were never disfigured with smallpox scars nor died from the illness. He realised that those who had had the milder form of cowpox were immune to smallpox. He gets the wonderful idea of finding an eight-year-old boy, infecting him with cowpox (from a cow called blossom) and then exposing him to smallpox some weeks later. Fortunately, the boy survives, we have our first vaccine and interestingly, our first vaccine sceptics who produce claims children will grow horns and develop patches like milk cows.

To take a slight tangent it wasn’t Jenner who made this discovery of immunisation. John Fewster in Thornbury Gloucestershire had heard of an ancient method of rubbing small amounts of smallpox pus into an incision on healthy individuals. Unfortunately, 2-3% of people died from this method. He was, however, stunned when a smallpox scar never formed on a farmer. The farmer explained had recently been infected with cowpox. Fewster and Jenner were part of the same medical society and likely had discussed Fewster’s observations and this ancient concept of rubbing pus into wounds from Asia.

So, it all sounds like the vaccine used was from cowpox right? Advance a few years to 1939 and scientists test the vaccine for cowpox antibodies and discover it’s not cowpox.

There are many mammalian pox viruses including horsepox, camelpox, buffalopox, rabbitpox, mousepox and raccoonpox. Being immune to one usually gives you immunity to others hence why the reproduction of smallpox vaccine to protect humans against monkeypox.

So, if it’s not cowpox, what are we injecting? One theory was horsepox. Prior to Jenner scraping pus off what he thought was cowpox of a young maid milking blossom; an undergardener to the Earl of Berkeley had inadvertently transferred horsepox to his cattle. When said undergardener came to Jenner for his vaccine, it didn’t work despite multiple attempts. He never got a little scar from cowpox. Could this undergardner have actually transferred horsepox to cattle, or was he just immune because he had horsepox? Jenner relied on transferring pus from one human arm to another. When that chain broke, he had to look for an infected cow and in 1817 when that failed he switched to using horses. This worked so well he would transport infected equinated lymph nodes to spread his vaccines. Could this have been when the cowpox-based inoculation began to be replaced with one made from horsepox? Or was the virus always horsepox that had been transferred to cows?

An international team of scientists in 2017 found an old sample of a lymph vaccine kit and did a gene sequence. They didn’t find cowpox, but something related to horsepox. Other teams have had simar results, no one has ever found cowpox in these vaccine samples. So it looks like the majority of 19th and 20th Century vaccines were really horsepox. This means either cowpox was never used or the switch in vaccines happened rapidly.

But my answer said vaccinia, not horsepox. A final twist. In 1930 there was a radical shift in vaccines used. This shift is from horsepox to a mystery virus called vaccinia. No one knows the origin and it hasn’t been found in the wild. Remember I said that the original production line was pus from human arm to human arm. Then they decided to put the virus back into animals, either cows, horses, sheep or donkeys to increase production. As production stepped up globally, we suspect someone harvested what they thought was cow or horsepox from another farm animal. It was an unidentified imposter. It worked well, so no one noticed. The mystery virus became the dominant strain and in 1966 when the WHO announced the smallpox eradication campaign, it chose six vaccine strains, one of which was vaccinia. With each passing decade, vaccinia becomes more prominent and is now what we have left. Why no natural host? Horsepox has been eradicated in the wild due to smallpox vaccinations. If vaccinia is so effective, we’ve likely eradicated it from its natural host.

References

• BBC.com The mystery virus that protects against monkeypox. Accessed Nov 2022