The Monkeypox virus or monkey pox currently gives rise to several epidemics around the world, and particularly in the United States and Europe.
According to the latest report from Public Health France, 2,239 cases were identified in France on Tuesday noon, including a majority of cases (1,375) reported in Île-de-France. 45 cases were hospitalized, including 37 for complications related to monkeypox.
In order to anticipate the introduction of this virus in French Polynesia, the country has authorized the marketing of the vaccine once morest monkey pox, the specialty IMVANEX.
French Polynesia authorizes the vaccine which would make it possible to vaccinate the population which would be identified at risk of being contaminated once morest smallpox. Procurement procedures are underway.
It is a vaccine once morest human smallpox, a fatal disease eradicated in 1980, which is currently used once morest monkeypox.
These two viruses are part of the “orthopoxvirus” family. The serum uses a third virus of this family, genetically close, that of the vaccinia.
The vaccine, harmless in humans, enabled the British doctor Edward Jenner in the 18th century to develop the very principle of vaccination (and to create the first anti-smallpox vaccine): to educate the immune system by confronting the organism with a virus close to the one to be fought.
“There is 90-95% homology of the viral proteins involved between the pox and monkeypox viruses. So taking a very close vaccine to block it is a proven strategy,” says Olivier Schwartz, head of the virus and immunity unit at the Institut Pasteur.
The current vaccine, made on cell culture and no longer on animals, is said to be “third generation because it has been improved compared to the two previous ones to limit side effects”, specifies Yannick Simonin, lecturer at the University of Montpellier. , specialist in emerging viruses.
What protection?
Smallpox infection confers cross-protection once morest the monkeypox cousin virus, a similar mechanism with the smallpox vaccine once morest monkeypox.
Although there are not yet large-scale data, past epidemiological elements and laboratory tests suggest that the current anti-smallpox vaccine will be highly effective once morest monkeypox.
“The vaccine protection figure of 85% dates from field studies in the 1980s-1990s in Zaire and is quite approximate”note Olivier Schwartz.
He also mentions studies in caregivers in 2018 and experiments on macaques that seem to show a strong effectiveness of post-exposure vaccination to monkeypox.
Having been vaccinated once morest smallpox before 1980 provides a priori immune protection once morest monkeypox, of an uncertain extent and duration.
“According to studies, for example from the 2000s, antibodies once morest smallpox were found in 30% of people vaccinated at least 20 years earlier,” says the Pasteur researcher. And “a booster dose will activate memory cells – B or T lymphocytes – and reactivate cellular immunity, even following 20 or 40 years”.
Yannick Simonin warns, however, that immunity “decreases over time and that the persistence of neutralizing antibodies once morest monkeypox has never been evaluated”.
What output?
The only vaccine currently authorized for monkeypox is manufactured by the Danish Bavarian Nordic, from the viral strain MVA-BN (modified vaccinia Ankara virus).
It is marketed as Jynneos in North America, Imvanex in Europe.
Several countries and the WHO keep stocks of smallpox vaccine for security, particularly in the face of a bioterrorism risk. Bavarian Nordic partnered with US authorities in 2003, and has already delivered 30 million doses to them. Since the current outbreak of monkeypox, an agreement provides for 7 million additional doses.
According to the WHO, there are currently 16 million doses of MVA-BN in the world, mostly in bulk, which would require a few months before being bottled to use them. It is difficult to know the state of the stocks, the countries opposing defense secrecy to the chagrin of associations and elected officials.
We also do not know the details of the orders from the only current manufacturer. The EU has so far ordered 100,000 doses.
Bavarian Nordic has an annual production capacity of 30 million doses. Two other smallpox vaccines, LC16 and ACAM2000, produced by other laboratories, are under study. Emergent BioSolutions, the American laboratory that produces ACAM2000, told AFP that it has an annual production capacity of 18 million doses, which might reach 40 million doses per year if necessary.
What distribution?
Despite the presence in part of the continent of areas endemic for monkeypox, more than 3,000 confirmed cases and, according to doctors, more than 70 potential deaths, Africa still has no dose of the vaccine.
The WHO has asked countries with vaccines to “share them with countries that do not have them”, calling not to reproduce the Covid-19 scenario, when rich countries have kept almost all of the vaccines for many months. vaccines available.
“Is there a risk that the countries submitting (requests) for access are rich countries? It’s entirely possible”, Meg Doherty, director of WHO programs on HIV, hepatitis, sexually transmitted infections, ruled on Sunday, demanding “fairness” on monkeypox at an International AIDS Conference.
