A smallpox vaccination is a vaccination which is designed to protect the recipient against smallpox. Smallpox is a virus which can cause fatal infections in humans. Smallpox has been eradicated from the wild, with the last documented case appearing in 1977, but some governments have expressed concern that it could be developed into a biological weapon. Vaccination against smallpox is no longer routine in most regions of the world although several governments have stocks of the vaccine and the ability to produce more if needed.
The smallpox vaccine was the first vaccine successfully developed and administered to humans. The modern version uses material from a related virus, cowpox or vaccinia, rather than smallpox itself. “Vaccinia” is actually the root of “vaccination,” a reminder of the fact that the smallpox vaccine was the first vaccine developed. People who receive the smallpox vaccination are protected from smallpox because the two viruses are similar, but they are not at risk of developing smallpox or passing it to others as a result of the vaccination.
This vaccine is not administered with a shot. Instead, a two-pronged needle is used. The bifurcated needle is dipped into a vial of live vaccinia virus and is used to quickly poke the skin several times. Within several days, a blister forms before resolving into a scab which falls off. The smallpox vaccination leaves behind a distinctive sunken scar, and for this reason it is often administered on an area of the body which is not readily visible.
Vaccination against smallpox provides immunity for three to five years. After this point, the patient will still have some immunity and resistance to the virus, but it will not be as strong. People who receive another smallpox vaccination will experience a boost in immunity and will also experience a lesser reaction to the second vaccine.
Immediately after smallpox vaccination, people can pass the cowpox virus to the people around them. It is important to be aware of this and to exercise caution around people who have not been vaccinated or who have compromised immune systems. Smallpox vaccinations today are generally administered to people who are believed to be at risk of contracting the virus, such as people who work with the virus in a research capacity or people who are in the military. Military personnel are heavily vaccinated against potential biological weapons because they may be at risk in the line of duty.