By Jefferey Jaxen

During a live-streamed meeting of the World Health Organization’s (WHO) briefing on monkeypox. General-Director Tedros Adhanom Ghebreyesus declared the virus outbreak a public health emergency of international concern.    

The targeted states and communities where cases are clustering are being directed to vaccinate by public health officials in hopes of stoping the spread. However, a major concern was voiced during that same WHO meeting by Unit Head of Global Infectious Hazards Preparedness at the WHO Tim Nguyen, when he stated: 

“I would like to underline one thing that is very important to WHO. We do have uncertainties around the effectiveness of these vaccines because they haven’t been used in this context and this scale before. And therefore, we are working with our member states, that when these vaccines are being delivered, that they are delivered in the context of clinical trial studies and prospectively collecting this data to increase our understanding on the effectiveness of these vaccines.” 

On June 28, HHS announced they would provide 296,000 doses of Bavarian Nordic’s JYNNEOS vaccine. Then, on July 1 they announced an order of an additional 2.5 million doses of the FDA-licensed vaccine indicated for prevention of smallpox and monkeypox yet stated that deliveries from this latest order will begin arriving at the Strategic National Stockpile (SNS) later this year and will continue through early 2023.

In concurrence with Nguyen’s warning to the WHO, the CDC similarly states: “We do not know if JYNNEOS will fully protect against monkeypox virus infection in this outbreak. Individuals wanting to minimize their risk of infection should take additional preventive measures and self-isolate as soon as they develop monkeypox symptoms, such as a rash.”

The 2019 approval of the JYNNEOS vaccine by the FDA, a third-generation monkeypox vaccine, was in-part a response to the poor safety profile of the 2007 FDA-approved, second-generation ACAM2000 vaccine which produced higher rates of heart inflammation and was contraindicated in severely immunocompromised people. Concerning the ACAM2000, the CDC websites states: 

“Adverse events following ACAM2000, including myopericarditis or Vaccinia virus transmission to household contacts, can be serious. ACAM2000 will be made available for individuals who decide in consultation with their healthcare provider that the potential benefits of vaccination outweighs any potential risks from ACAM2000 adverse events.”

However, during two of the pivotal clinical trials evaluating the JYNNEOS vaccine, a significant number (18.4%) of subjects were reported to have abnormal troponin levels, a indicator that damage to the heart has occurred, following vaccination

The WHO first reported there was no evidence the monkeypox virus had mutated three weeks after the first case was identified in the UK. That proclamation soon gave way to reports of two distinct variants circulating on June 3 according to the CDC. 

Being a DNA virus, monkeypox has a more stable genetic code and a vastly slower mutation rate than the RNA-based coronavirus meaning variants aren’t produced as rapidly.