Fridge-free tetanus-diphtheria vaccine shows promise in first human trial

A phase I clinical trial has demonstrated that a reformulated tetanus-diphtheria vaccine can remain stable and effective without refrigeration, potentially expanding access in regions where cold-chain infrastructure is limited. The vaccine, designated SPVX02, was developed by UK biotech company Stablepharma using its StablevaX thermostabilisation platform.

The randomised, single-blind trial enrolled 60 healthy adults at the NIHR Clinical Research Facility at University Hospital Southampton and the Medicines Evaluation Unit in Manchester. By 28 days after vaccination, all participants receiving SPVX02 achieved protective antibody levels against both tetanus and diphtheria, with immune responses comparable to those from licensed refrigerated vaccines.

The study reported no vaccine-related serious adverse events, indicating the candidate was well tolerated. Researchers also showed that SPVX02 retains full potency after storage at temperatures up to 30°C (86°F) for at least two years and survives three cycles of extreme temperature fluctuation between -20°C and +40°C.

According to the World Health Organization, roughly half of all vaccines are wasted globally each year, largely due to temperature excursions during storage and transport. Eliminating the need for continuous refrigeration could reduce this waste and lower the carbon emissions associated with cold-chain logistics.

Professor Saul Faust of the University of Southampton, who led the study, said the findings suggest the vaccine can remain safe and effective without refrigeration. If confirmed in larger trials, the technology could transform how vaccines are stored and delivered worldwide.

A phase 2b trial has been launched to evaluate SPVX02 in a larger participant group. Stablepharma is also applying its StablevaX platform to other vaccines, small-molecule oncology drugs, and anti-infective products in partnership with other developers.

The peer-reviewed results were published in eClinicalMedicine. The research was supported by the National Institute for Health and Care Research (NIHR) Biomedical Research Centre Southampton and the NIHR Clinical Research Facility.