The smallpox vaccine Imvanex, developed by Bavarian Nordic, has received a recommendation from the European Medicines Agency’s (EMA) Committee for Medicinal Products for Human Use (CHMP) that it can be given to adults to prevent monkeypox.
Specifically, the CHMP has recommended extending the indication of this drug to include the protection of adults against monkeypox. This vaccine was approved in the European Union in 2013 to prevent smallpox, but not monkeypox, however, in many European countries it was already being administered to try to stop the outbreak that started a few months ago, since there was scientific evidence that suggested it is effective against this other form of smallpox, and had already received approval for this use in the United States.
Safety and efficacy of the Imvanex vaccine
Imvanex works by preparing the body to defend itself against infection with the variola (smallpox), monkeypox, and vaccinia viruses. It contains a weakened form of the vaccinia virus called ‘modified Ankara vaccinia virus’, which is linked to the smallpox virus and monkeypox, but does not cause any disease in people because it is not able to reproduce in human cells.
Imvanex was approved in Europe since 2013 for smallpox, now its use is extended in adults against the monkeypox emergency
When a person is given the vaccine, their immune system recognizes the vaccine virus as ‘foreign’ and makes antibodies against it. When the vaccinated person comes into contact with similar viruses, these antibodies, along with other components of the immune system, will be able to eliminate those viruses.
The CHMP recommendation was based on the results of several animal studies in which Imvanex was found to provide protection against monkeypox virus in vaccinated non-human primates. The CHMP considered that the efficacy of Imvanex in preventing monkeypox in humans “could be inferred from these studies”. The EMA has stated that “the drug’s safety profile is favourable, with mild to moderate side effects. The benefits of the drug outweigh the risks.”
Monkeypox can be deadly
Although it is usually milder than smallpox, monkeypox can also be deadly. Initial symptoms are fever, headache, muscle aches, tiredness, and swollen lymph nodes. After one to three days, a rash usually appears on the face, which spreads to other areas of the body, including the extremities (hands and feet). In addition, a recent international study has identified new symptoms, such as genital lesions and anal pain, among others.
The disease is a zoonosis that is transmitted to people through wild animals, such as rodents and primates, but the infection can also be transmitted between people by direct or indirect contact, and the virus has been found in samples of saliva, semen and urine of infected individuals. The outbreaks that have been reported since May 2022 are the first outside Africa without links to endemic areas.
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