EU Approves Monkeypox Vaccine (Imvanex) by Danish Biotech Firm

The smallpox vaccine produced by Bavarian Nordic was approved against monkeypox in Europe.

Photo by Jerico Stokovic Lee on Pexels.

On July 25th, the European Commission has approved the use of Bavarian Nordic’s smallpox vaccine against monkeypox. The approval came two days after the World Health Organization announced the disease has become a Public Health Emergency of International Concern.

Imvanex is a third-generation smallpox vaccine produced by Danish biotechnology firm Bavarian Nordic, and it is based on a modified strain of the Vaccinia virus Ankara (MVA). A virus that belongs to the same family as the Variola virus responsible for smallpox, and that is used to induce immunity against it.

This modified strain, technically known as MVA-BN, was developed in chicken cells and therefore cannot replicate in humans. This makes Imvanex safer when compared to second-generation smallpox vaccines, which were based on replication-competent Vaccinia viruses. As a safer vaccine, it can also be given to immunocompromised patients, unlike previous ones.

However, there is a downside to these third-generation vaccines. Imvanex has never been field tested, given that smallpox was eradicated before the vaccine was approved by the European Commission in 2013 — and later by Canada and the United States, under the brand names Imvamune and Jynneos, respectively.

Approving and acquiring a vaccine for a disease officially eradicated in 1980 may sound strange, but there are a few good reasons to do so. The first is the possibility that smallpox can naturally re-emerge and cause devastating outbreaks once again. If not naturally, then there is also the risk of an accidental laboratory leak from institutes that study the disease — albeit extremally unlikely. For these reasons, it is mandatory for researchers working on smallpox to be vaccinated against it.

The third (and possibly strongest) reason why countries like Canada and the United States have stockpiled smallpox vaccines is biological defense. That is, to protect their population in case smallpox is ever used against them as a biological warfare weapon. One of the most infamous examples used to justify this is the 1971 Aral Sea Incident, where a field test of weaponized smallpox reportedly caused an outbreak in Kazakhstan.

More recently, a fourth reason to produce smallpox vaccines emerged in Africa by the name of monkeypox. First detected in humans in 1970, monkeypox cases have been reported in non-endemic countries since 2003, and have now spread wide enough to cause a global outbreak.

Given that the monkeypox virus is closely related to both Variola and Vaccinia viruses (which all belong to the Orthopoxvirus genus), smallpox vaccines also confer immunity against monkeypox infections through cross-immunization. More precisely, they have roughly 85% effectiveness against it.

Unfortunately, data on the effectiveness of these vaccines when it comes to monkeypox is rather scarce. In fact, the numbers mentioned are based on a 1988 non-randomized observational study led in the Democratic Republic of the Congo — at a time when the vaccines used were first-generation smallpox vaccines, which are no longer available.

Nevertheless, countries like the United Kingdom, Canada, and the United States have extended the approval of the smallpox vaccine to also cover monkeypox. These are joined as of July by the European Union, Iceland, Liechtenstein, and Norway. An approval that was prompted by the ongoing global monkeypox outbreak — with the European Medicines Agency citing animal studies in support of the decision.

With Spain and Brazil now reporting the first monkeypox-related deaths outside of Africa on July 29th. Europe will soon follow the United Kingdom, Canada, and United States in launching a preventive vaccination campaign against the disease. These campaigns have inevitably caused a growing demand for Imvanex vaccines, leading Bavarian Nordic’s share prices to rise by 122%.

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Gil Pires

Gil Pires

Junior Consultant | MSc in Biotechnology