Phase I

Phase II

Phase III

Smallpox and Mpox (Monkeypox) Preventing Vaccine


Tonix has developed an attenuated, one-dose, live orthopoxvirus (horsepox) vaccine candidate (TNX-801) with the potential capability to protect against smallpox and Mpox (monkeypox). We have shown in non-human primate (NHP) studies that the vaccine was well-tolerated, safe, and produces innate, humoral and T-cell immunity and has the potential to reduce forward transmission after virus challenges1. It is a 4th generation vaccine which uses synthetic biology in its design. Horsepox vaccine activity against smallpox was first noted by Jenner in the 18th century and Next Gen sequencing has shown >99% homology between it and “vaccinia” used successfully in smallpox eradication starting in the 19th century2. At present, the threat from smallpox (laboratory escape and rogue actors) and the lethal Clade 1 Mpox (natural outbreaks) is seen by experts as unacceptably high3 making TNX-801 development timely. Multiple further studies4,5 have shown TNX-801 to be 10-1000 times as attenuated as earlier 2nd generation vaccinia virus (ACAM2000), the predominant government stockpile vaccine for use in the event of a wider scale smallpox or Mpox epidemic. This is important because this older generation vaccinia virus vaccine comes with an unacceptable risk for myo/pericarditis side effects6. A 3rd generation smallpox vaccine (Jynneos) requires 2 doses and is limited in manufacturability and cost for population wide use, further highlighting the potential value of TNX-801 in biodefense preparedness and epidemic response.

1Noyce RS, et al S. Single Dose of Recombinant Chimeric Horsepox Virus (TNX-801) Vaccination Protects Macaques from Lethal Monkeypox Challenge. Viruses. 2023 Jan 26;15(2):356. doi: 10.3390/v15020356. PMID: 36851570; PMCID: PMC9965234.
2 Schrick L et al. N Engl J Med. (2017) 377:1491-1492.
3Bipartisan Commission on Biodefence (2024) Box the Pox
4Awasthi M, et al Immunogenicity and Tolerability of a SARS-CoV-2 TNX-1800, a Live Recombinant Poxvirus Vaccine Candidate, in Syrian Hamsters and New Zealand White Rabbits. Viruses. 2023 Oct 21;15(10):2131. doi: 10.3390/v15102131. PMID: 37896908; PMCID: PMC10612059.
5Trefry SV et al Recombinant chimeric Horsepox Virus (TNX-801) is attenuated relative to Vaccinia Virus Strains in Human Primary Cell Lines and in Immunocompromised Mice bioRxiv 2023.10.25.564033; doi:
6National Acedemies . Future State of Smallpox Medical Countermeasures.2024 : National Academies Press

TNX-801 is an investigational new biologic and has not been approved for any indication.