Scanning electron micrograph of monkeypox virus (orange) on the surface of infected VERO E6 cells (green).
[Image courtesy of NIAID]
While vaccination efforts are ramping up, California, New York and Illinois have declared states of emergency as the monkeypox virus spreads.
As the monkeypox outbreak continues to gain momentum, here are three questions to keep in mind.
1. How effective are monkeypox vaccines?
CDC notes that the effectiveness of the vaccines is unknown in the current outbreak.
While some media outlets have reported that the smallpox vaccines are 85% effective in protecting against monkeypox, that figure is based on a small study in Africa from 1988.
That study followed the household contacts of 209 monkeypox-infected individuals in Zaire.
Of those, 70% had scars from prior smallpox vaccination. Those vaccinated individuals were 85% less likely to be infected with monkeypox than the remaining 30%.
The data from the study are “pretty weak,” concluded the University of Florida biostatistician Ira Longini in an interview with MedPage Today.
Still, Jynneos and ACAM2000 rely on newer, potentially more effective vaccine technology than was available in the 1980s.
A 2008 study published in PNAS found that a smallpox vaccine offered protection for over two years in a monkeypox virus challenge model involving non-human primates.
2. Will other monkeypox vaccines enter the fray?
Monkeypox vaccine doses are in short supply. Bavarian Nordic is planning to close a European production facility until late 2022.
In late July, FDA authorized 786,000 doses to be distributed in the near future following an FDA expedited inspection of Bavarian Nordic’s fill-and-finish capabilities. The U.S. has been working to procure 5.5 million monkeypox vaccine doses for 2023.
A handful of other companies could potentially introduce monkeypox vaccines. Moderna said it engaged in preclinical testing of potential monkeypox vaccines.
On a related note, Siga Technologies has noted that it has received approximately $13 million worth of orders for its oral smallpox antiviral, Tpoxx (tecovirimat). FDA approved the drug in 2018 based on data from animal studies. Although not authorized specifically for monkeypox, Tpoxx is available as a treatment for the virus through an investigational drug protocol.
Emergent BioSolutions also acquired the oral antiviral Chimerix’s Tembexa, which won FDA approval in 2021.
3. Will developing nations continue struggling with monkeypox vaccine access?
In the COVID-19 pandemic, wealthy nations purchased the bulk of available COVID-19 vaccine doses, leaving those in low and middle-income countries with limited access to vaccines.
A similar phenomenon appears to be playing out with the monkeypox outbreak. Wealthy countries have yet to announce plans to offer vaccine doses to the developing world.
The situation could exacerbate health outcomes in regions such as Africa. For example, the Congo Basin strain of monkeypox circulating in the Democratic Republic of the Congo and the Central African Republic is approximately 10 times more lethal than strains circulating elsewhere, according to an article in Science.
Filed Under: Infectious Disease
