Smallpox was one of the deadliest viral diseases in history, with an estimated 30 percent of those infected died. Therefore, a global vaccination program was initiated in 1959, and in 1980 the World Health Organization (WHO) declared the world smallpox-free.
But now a similar virus is spreading: monkey pox.
Old vaccine is 85% effective
Like smallpox, monkeypox belongs to the poxvirus family. A new monkey pox vaccine has been developed, Jynneos.
But demand exceeds supply, which is why it has been proposed to use the old smallpox vaccine as well.
Both vaccines contain a smallpox virus, the vaccinia virus, which commonly infects cattle. The virus is used because it is virtually harmless to humans, but does stimulate the immune system to make antibodies against smallpox viruses in general.
The antibodies are therefore active against both smallpox and monkeypox.
However, doctors are hesitant to use the old smallpox vaccine because, unlike the new variant, it contains live virus.
After the vaccination, the puncture site must therefore be treated with care, because anything that has come into contact with it (clothing, plasters) can spread the virus.
People who have had the smallpox vaccine are 85% protected against monkeypox for three to five years. But after that, the effect wears off. So if you were vaccinated more than 40 years ago, you are no longer protected.