The world-first trial of a fridge-free tetanus-diphtheria vaccine has produced encouraging results that could improve access worldwide to crucial treatments, while reducing carbon emissions.
Around half of vaccines are wasted globally each year, according to the World Health Organization. Millions of vaccine doses are lost because of temperature changes during storage and transport. Fridge-free vaccines have the potential to transform vaccine delivery by reducing this dependence on refrigeration. This would improve access in more isolated communities and cut the environmental impact by reducing vast amounts of energy that lead to emissions.
The phase I study found the vaccine was well tolerated, with no vaccine-related serious adverse events. Results have been published recently in The Lancet group’s eClinicalMedicine.
The reformulated vaccine, known as SPVX02, was developed by UK-based biotech company Stablepharma using its StablevaX technology. The trial took place in the National Institute for Health Research (NIHR) Clinical Research Facility at University Hospital Southampton and was delivered through the NIHR Biomedical Research Centre: Southampton.
The research shows that SPVX02 can be stored at temperatures of up to 30°C for at least two years without losing its effectiveness. Scientists are now investigating whether it can remain stable for as long as four years. Researchers have also demonstrated that the vaccine remains stable, and fully potent, after three cycles of extreme temperature fluctuation from -20°C to +40°C.
The randomised trial, which also involved the Medicines Evaluation Unit (MEU) in Manchester, enrolled 60 healthy adults. By 28 days after vaccination, all participants receiving SPVX02 achieved protective antibody levels against both tetanus and diphtheria, demonstrating immune responses comparable to licensed vaccines.
The eClinicalMedicine publication follows the launch of a Phase 2b trial that will further assess the vaccine in a larger group of participants. Stablepharma's technology platform, StablevaX, can be applied to vaccines, small molecules, peptides and biologics. The company is currently working with a partner to thermostabilise small molecule oncology and anti-infective products, in addition to other vaccines.
Professor Saul Faust, Director of the NIHR Clinical Research Facility in Southampton and Professor of Paediatric Immunology and Infectious Diseases at the University of Southampton, who led the study, said: “Keeping vaccines cold from the factory to the patient is one of the biggest challenges facing immunisation programmes worldwide. Our study suggests that this vaccine can remain safe and effective without refrigeration. If larger studies confirm these findings, this technology could help transform the way vaccines are stored and delivered around the world.”
NIHR-funded research infrastructure enabled Stablepharma to conduct this first-in-human trial and generate the clinical evidence needed to advance this UK-developed technology.
This shows how the UK’s research system works with innovative companies to translate promising science into globally relevant products, opening up new markets and making vaccines easier to store, transport and deliver around the world.
Stablepharma’s SPVX02 vaccine has been developed with support from Innovate UK, part of UK Research and Innovation (UKRI). It is a reformulated version of the WHO-prequalified Tetadif tetanus-diphtheria vaccine. Scientists from the UK Health Security Agency (UKHSA) provided specialist laboratory testing.
Stablepharma expects to complete the clinical development programme for SPVX02 by 2027.
- Reed TAN, Clarke P, de la Torre Arrieta J, et al. Safety, tolerability, and immunogenicity of SPVX02, a room temperature-stabilised tetanus-diphtheria vaccine, compared to two established tetanus-diphtheria booster vaccines: a multicentre, single-blind, randomised, first-in-human phase 1 trial in the UK. eClinicalMedicine 2026. Published online 5 August. doi: 10.1016/j.eclinm.2026.104116