Clade I, the culprit in the current 2025 version of global epidemic mpox, is highly transmissible and is spreading within families and among children, whereas the 2022 Clade II mpox - still spreading - infects mostly gay men
CHATHAM, NJ / ACCESS Newswire / March 20, 2025 / This post was written and published as a collaboration between the in-house editorial team at Benzinga and Tonix Pharmaceuticals Holding Corp. with financial support from Tonix. The two organizations work to ensure that any and all information contained within is true and accurate as of the date hereof to the best of their knowledge and research. This content is for informational purposes only and not intended to be investing advice.
A new strain of mpox, previously known as monkeypox, is spreading around the world, prompting the World Health Organization to further extend its public health emergency of international concern which had been put in place for the second time in two years.
This new Clade I mpox is different from the version that spread rapidly around the world in 2022 and infected mostly gay men, called Clade II. The new version spreads within families and affects children. For reasons not fully understood, children are playing an outsized role in transmission of the new virus and are also more susceptible to severe disease. That is worrying health officials since to date, there isn't an effective way to stop the spread of this infectious disease.
Single Dose Vaccine on the Horizon?
Tonix Pharmaceuticals Holding Corp. (NASDAQ:TNXP), a biopharmaceutical company with marketed products and a pipeline of development candidates, is hoping to change that with its TNX-801 vaccine candidate. TNX-801 is a live, minimally replicating, recombinant virus vaccine based on synthesized horsepox that the company says has been shown to provide single-dose immune protection against a monkeypox challenge with better tolerability than 20th-century vaccinia live-virus vaccines in animals. TNX-801 has previously been shown to protect animals against lethal challenge with intratracheal clade I monkeypox virus, reports Tonix.
According to Tonix, after a single dose vaccination, TNX-801 prevented clinical disease and lesions and also decreased shedding in the mouth and lungs of animals challenged with clade I monkeypox. What's more, Tonix reported during a presentation at the World Vaccine Congress-Europe 2024 that TNX-801 does not spread in blood or tissues in these animals, even at an approximately 10 to 1000-fold higher dose than 20th-century vaccinia vaccines. These findings are consistent with TNX-801 inducing mucosal immunity and suggest TNX-801 has the ability to block forward transmission, reports the company.
"Data continue to support TNX-801's strong tolerability and efficacy profiles by continually displaying protective immunity to animals with single-dose administration," said Seth Lederman, M.D., CEO of Tonix. "Synthetic biology is an important technology for vaccine development as viral diseases continue to rapidly evolve. With TNX-801's target profile, favorable shipping and storing requirements and our manufacturing collaboration agreements, we believe TNX-801 is in a strong position to make an impact towards preventing mpox and controlling mpox epidemics."
Current Vaccine Limitations
Two mpox vaccines are available, both with limitations, prompting the WHO to look for additional remedies. The Jynneos® vaccine from Bavarian Nordic, requires two doses to provide full protection and is associated with potential waning immunity over time which could require booster shots. Jynneos is only 66% effective against mpox with two doses, and 35.8% with a single dose, according to a major study published in the New England Journal of Medicine. The second vaccine, ACAM2000 from Emergent BioSolutions, has side effects, including large lesions at the injection site. Tolerability issues limit the use of this vaccine in the U.S. to only those people at high risk of exposure to smallpox and mpox and not likely to be become available commercially as it also requires specialized training to administer.
The WHO has stated it is looking for vaccines that are single dose, have durable protection, can be administered without special equipment and are stable at ambient temperature. After all, a single-dose vaccine reduces the likelihood of dropouts between doses and enables the more efficient "ring vaccination" strategies. These are critical for controlling outbreaks and preventing the virus from spreading beyond the initial clusters of cases, which can quickly spiral into larger outbreaks if not contained early.
Vaccines that can limit forward transmission and are effective for use in immunocompromised individuals are also on the WHO's list. Tonix says TNX-801 fits the bill, aligning with those requirements, and that its focus on single-dose vaccines adheres to recommendations by the Bipartisan Commission on Biodefense and the U.S. National Academies of Sciences.
Manufacturing for the Masses
The production of TNX-801 uses conventional cell culture systems, which should facilitate mass production and potentially make the TNX-801 vaccine available on a global scale, ensuring that regions most in need have access once approved for use by local regulatory agencies.
Mpox cases are rapidly spreading around the world, and the new Clade I strain has now appeared at least three time in the U.S. Vaccine supplies are limited, particularly in Africa where the need seems to be the greatest. With the current trends in the spread of mpox, the demand for single-dose vaccines that are provide durable immunity with acceptable tolerability is bound to increase. Tonix Pharmaceuticals is hoping to deliver on that demand with TNX-801. If preclinical trials are any evidence, the biopharmaceutical company may be worth keeping an eye on.
* TNX-801 is an investigational new biologic, neither its efficacy nor safety have been demonstrated and it is not approved for any indication.
This post contains sponsored content. This content is for informational purposes only and not intended to be investing advice.
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