Smallpox vaccination: scar as a lifelong memory

If the course of the disease is mild, the blisters dry out after two to three weeks and the scabs fall off. From then on, the sick person is no longer contagious. Overall, this process takes about four weeks – small, punctiform scars remain. These are distinctly different from the scar resulting from smallpox vaccination.

To immunize the body, unvaccinated people received a live smallpox vaccine made from, for example, the related vaccinia virus (cowpox). In this way, the immune system was confronted with live smallpox viruses, which, however, were weakened and therefore less dangerous. This allowed the body to produce antibodies against the virus.

The World Health Organization (WHO) succeeded in eradicating smallpox through strict quarantine regulations and a worldwide vaccination campaign started in 1967.

Doctors used a special needle or (temporarily) a vaccination gun to vaccinate smallpox:

• Scratching with bifurcation needle: In this method, the vaccine was scratched into the skin (scarification) using a two-piece needle. The doctor briefly dipped the needle into the vaccine solution so that part of the liquid could collect between the two needle tips and be injected into the skin. To ensure that the vaccine reached the middle layer of the skin, about 15 controlled stitches were performed in a circular fashion. Here, the vaccinating person had to be careful not to come into contact with the live vaccine and become infected.
• vaccination gun: Using only high pressure, the vaccination gun injected the vaccine through the skin into the connective tissue. The vaccine was already pre-dosed here, so that a vaccination gun could vaccinate several doses in a row.

The bifurcation needle required only a quarter of the vaccine. It was therefore more economical and easier to use. The eradication of smallpox is therefore partly due to her. The vaccination gun, on the other hand, turned out to be unwieldy and unreliable in comparison. In order not to slow down the vaccination campaign, the WHO ultimately used the bifurcation needle.

But even before the WHO vaccination campaign and the development of the vaccination gun and bifurcation needle, smallpox was vaccinated, although the vaccination techniques differed somewhat. For example, a common method was to put a drop of vaccine on the skin and then scratch it.

Doctors could not only vaccinate against smallpox as a preventive measure, but also after a person had already had contact with the virus. However, the so-called incubation vaccination had to be carried out within a period of four to seven days after initial contact with the smallpox virus. This was the only way to prevent the disease from breaking out or at least to mitigate and contain the course of the disease. However, if the rash had already started, the incubation vaccination no longer offered any protection. The sick person was now highly contagious.

Most people today can only tell whether they have been vaccinated against smallpox or not by the light-colored scar on their upper arm. However, this has nothing to do with whether a bifurcation needle or an inoculation gun was used. Rather, it is a consequence of the vaccination technique and the vaccination reaction.

At that time, the smallpox vaccine was injected specifically into the skin (intradermally or intracutaneously). As a result, a controlled infection developed at the vaccination site after about a week, a pustule that indicated the successful immune reaction. The blister then healed and a crust formed over it. After this crust fell off, a scar remained and is a reminder of the successful smallpox vaccination. From then on, vaccination protection should be guaranteed for about three to five years.

If people had regular contact with smallpox viruses, a booster vaccination could be carried out after this time, which should offer them protection for up to 30 years. Those who received this second smallpox vaccination now bear two of the oval scars on their upper arms.