As Mpox Cases Spread Around the World, Tonix Pharmaceuticals’ Single-Dose Vaccine TNX-801 Has Potential to Slow the Spread

Rhea-AI Summary

Tonix Pharmaceuticals (NASDAQ:TNXP) is developing TNX-801, a single-dose vaccine candidate for mpox, as global cases of the new Clade I strain continue to spread. The current outbreak has caused over 45,000 cases and 1,400 deaths since 2022, with a 3% mortality rate primarily in African countries.

Unlike the 2022 Clade II outbreak that mainly affected gay men, the new Clade I variant spreads within families and particularly affects children, who are more susceptible to severe disease. TNX-801, based on synthesized horsepox, has shown promising results in animal studies, providing single-dose protection against Clade I mpox with better tolerability than traditional vaccinia vaccines.

Current vaccines have limitations: Jynneos requires two doses and is only 66% effective with full dosing, while ACAM2000 has significant side effects. TNX-801 aligns with WHO requirements for an ideal mpox vaccine, offering potential single-dose protection, conventional manufacturing processes, and the ability to limit forward transmission.

Positive

• TNX-801 showed single-dose protection in animal studies
• Vaccine prevents clinical disease and reduces viral shedding
• Uses conventional manufacturing processes for potential mass production
• Better tolerability than traditional vaccinia vaccines

Negative

• TNX-801 is still in preclinical stage, not yet approved
• Efficacy and safety in humans not yet demonstrated
• Competing vaccines already in market despite limitations

News Market Reaction

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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.

Click here for an 8 -minute video of Seth Lederman, M.D. reviewing the status of TNX-801 for mpox

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.

While over 45,000 cases and 1,4000 deaths so far since 2022 have been in African countries , representing a 3% mortality rate, it's been showing up in new places, including the U.S. In November 2024, the California Department of Public Health confirmed the first reported case of clade I mpox, in the U.S. Since then, cases have been reported in New Hampshire, Georgia and in New York . Germany has reported seven new cases. All told, this strain of mpox has been reported in dozens of African countries and in Canada, India, Sweden, Thailand and the U.K.

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.

Click here for more information on Tonix Pharmaceuticals:

Contact Information

Jessica Morris
Tonix Pharmaceuticals
investor.relations@tonixpharma.com
862.904.8182

SOURCE: Tonix Pharmaceuticals Holding

View the original press release on ACCESS Newswire

FAQ

What is the effectiveness of TNX-801 compared to existing mpox vaccines for TNXP?

In animal studies, TNX-801 showed single-dose protection against Clade I mpox, while Jynneos is only 66% effective with two doses and 35.8% with one dose.

How does the new Clade I mpox variant in 2025 differ from the 2022 outbreak?

The 2025 Clade I variant spreads within families and affects children more severely, while the 2022 Clade II outbreak primarily affected gay men.

What are the mortality rates and case numbers for the current mpox outbreak?

Since 2022, there have been over 45,000 cases and 1,400 deaths, with a 3% mortality rate primarily in African countries.

Which countries have reported cases of the new Clade I mpox variant?

Cases have been reported in the US (California, New Hampshire, Georgia, New York), Germany, Canada, India, Sweden, Thailand, UK, and dozens of African countries.