Smallpox vaccines given until the mid-1970s would provide continued cross-immunity against infectious disease due to an orthopoxvirus.
- The smallpox vaccine would provide about 80% protection against Monkeypox.
- People born before 1976 who had been vaccinated had a stronger immune response against both types of virus.
- Memory cells would be able to recognize viruses “closely related like the virus” of the monkey pox.
Since May 2022, cases of monkeypox or simian, which usually manifests as a rash, have been reported in Europe and around the world. Currently, the epidemic still concerns certain countries and the disease is subject to heightened surveillance. “The treatment of monkeypox consists of supportive care. Vaccines and treatments developed for smallpox and authorized by some countries can be used in certain circumstances for the treatment of the disease”, noted the World Health Organization (WHO).
Analyze T cell immune response
Several available data indicate that the classic vaccine against smallpox could protect us from Monkeypox. Researchers at the Karolinska Institute in Sweden have thus wondered whether people who were vaccinated decades ago were protected against monkeypox due to a residual memory response. In one study, the team analyzed the T-cell immune response in 105 healthy people, some of whom had been vaccinated against smallpox before 1976. Specifically, they measured T-cell reactivity to peptides specific for smallpox virus and Monkeypox.
Monkeypox: “about 80% protection” thanks to the smallpox vaccine
According to the results, published in the journal Cell Host & Microbe, adults born before 1976 who had been vaccinated had a significantly stronger immune response against both types of virus. The authors also analyzed the immune response of 22 men recently infected with smallpox and showed that they also had a strong immune response to the virus, which may provide future immunity.
“This implies that memory cells are very long-lived and can recognize closely related viruses like the mpox virus and provide overlap or cross-reactive immunity. This study shows that the smallpox vaccine can offer approximately 80% protection against monkeypox”, concluded Marcus Buggert, author of the work, professor and researcher at the Center for Infectious Medicine at the Karolinska Institute, in a statement.
