European Medicines Agency Considers Extension of Smallpox Vaccine Use for Monkeypox
JYNNEOS smallpox vaccine produced by Bavarian Nordic, approved by the FDA for use against monkeypox.

The European Medicines Agency is considering the extension of the use of the smallpox vaccine Imvanex to include people at risk of Monkeypox disease, the agency said on Tuesday. 

Imvanex is a modified form of the vaccinia virus, which is related to smallpox and currently authorised in the European Union (EU) for the prevention of smallpox in adults. But it is also considered a potential vaccine for monkeypox because of the similarity between the viruses, both of the Orthopoxvirus genus. 

Supplies of Imvanex limited in the European Union    

Supplies of Imvanex are currently very limited in the EU. However, the same vaccine is marketed as JYNNEOS in the US where it is authorised for the prevention of both monkeypox and smallpox. Full EMA authorization also would clear the way for broader use of the US vaccine brand in Europe.

The EMA review follows a recent recommendation by EMA’s Emergency Task Force (ETF) that JYNNEOS, produced by the Danish firm Bavarian Nordic, be used by European national authorities for at risk groups, in view of the rising rates of Monkeypox infection across the EU.

The US Food and Drug Administration has already concluded that the efficacy of JYNNEOS in the prevention of monkeypox disease can be inferred from antibody responses against the vaccinia virus in clinical studies.  In addition, animal studies showed that the vaccine protected those exposed to the monkeypox virus and boosted pre-existing immunity induced by earlier generations of smallpox vaccines.

3413 confirmed cases outside of endemic region

As of 22 June 2022, 3413 laboratory confirmed cases of Monkeypox and one death have been reported to WHO from 50 countries/territories in five WHO Regions, WHO reported in its latest Disease Outbreak News, on Monday 27 June.     

Another 1310 cases in eight new countries have been reported over the past ten days since the previous WHO update on 17 June

Even so, a WHO Emergency Committee that met last week last week deferred a decision on whether to declare Monkeypox a public health emergency of international concern (PHEIC), saying it would review the matter again in another three weeks. 

The Emergency Committee said its evaluation would be based on whether there had been further “significant spread” of the infection, particularly among vulnerable groups such as people with HIV, pregnant women and children.

The concerns over the spread of monkeypox in Europe and other developed countries, followed by moves like those of the EMA to prepare for the vaccination for at risk groups, have triggered fresh allegations of inequitable treatment amongst health officials in Africa’s Region, which has lived with the virus for years with no vaccine initiatives ever proposed or considered until the virus began to expand its boundaries.

New patterns of skin-borne transmission increases risks to other groups

Since the beginning of 2022, some 1597 cases – 1488 suspected and 109 laboratory-confirmed- of monkeypox have been reported in the nine central and west African countries where the disease circulates.  That data likely reflects significant under-reporting insofar as the disease is prevalent in remote rural areas where contact with infected wild animals such as rodents and squirrles is a major source of transmission.  A total of 66 deaths have been reported by Africa CDC – although WHO recently put the death toll at 72.

Either way, that is a case fatality ratio (CFR) of  4.1% or more on the continent, including all suspected cases. Some studies have shown Monkeypox mortality rates as high as 10% in the Democratic Republic of Congo – where the most virulent clade of the virus circulates.  

Monkeypox: Africa CDC Demands Equal Treatment in Global Allocation of Limited Vaccine Doses

Traditionally, monkeypox virus outbreaks in Africa, the result of zoonotic spillover events, saw limited person-to-person transmission.  In contrast, the outbreak in Europe and other non-endemic countries has been characterised by significant community transmission, often among men having sex with men. It is the increased pattern of skin-borne transmission of the virus that also increases risks to other vulnerable groups. 

WHO had pledged to come up with a plan for equitable distribution of monkeypox vaccines between at risk groups in endemic and non-endemic areas where the recent outbreak is being experienced.  However it remains to be seen if vaccine rollout is really feasible in conflict-ridden areas like the DRC and Central African Republic, where the disease is historically most prevalent, and deadly.  It’s equally unclear if and how developed countries, such as the United States, which controls much of the world’s limited smallpox vaccine supply, will heed WHO’s appeals.

Image Credits: Barda .

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