Every year, the **World Health Organization** estimates that up to **half of all vaccines produced worldwide never reach the people they were made for**.
Not because they weren't funded. Not because distribution networks don't exist. But because of something called the **cold chain** — the requirement that most vaccines be kept within a specific temperature range, typically 2–8°C, from the moment they leave the factory until the moment they're injected into a patient.
One power cut, one broken refrigerator, one flight delay, one remote community without reliable electricity — and the vaccines become ineffective and must be discarded. The cold chain is one of the most significant single barriers to global immunisation coverage.
A small UK biotech company may now have one of the most important parts of the solution.
**What SPVX02 Is**
**SPVX02** is a tetanus and diphtheria vaccine developed by **Stablepharma Ltd**, a UK-based pharmaceutical company. What makes it different from every other tetanus vaccine in clinical use isn't the disease it targets — it's how it's stored.
SPVX02 is **thermostable**: it remains effective without refrigeration after **24 months of storage at 30°C**. Not cool storage. Not ambient room temperature in a Northern European office. **30 degrees Celsius** — a temperature closer to outdoor air in many parts of Africa, South Asia, and Latin America where cold-chain failure is most acute.
For context, traditional tetanus vaccines must be kept between 2°C and 8°C at all times. At temperatures above that threshold, the active compounds begin to degrade. There is no recovery: once the cold chain is broken, the vaccine is typically discarded.
**Phase 1 Trial Results**
Phase 1 human trials of SPVX02 have now been completed, with testing conducted at the **UK Health Security Agency's Vaccine Development and Evaluation Centre (VDEC)** — one of the world's leading vaccine evaluation facilities.
The results are encouraging: SPVX02 **remains immunogenic and effective** after extended storage at elevated temperatures, without losing potency. UKHSA's evaluation of the trial confirms the vaccine meets the required standards for progressing to the next stage.
The programme will now advance to a **Phase 2 trial** comparing SPVX02 directly against an existing licensed tetanus and diphtheria vaccine, with a larger cohort of healthy participants at clinical study sites in the UK. UKHSA will continue providing laboratory support to measure immune responses.
**How Stablepharma's Technology Works**
Stablepharma has developed a proprietary **formulation platform** — not a change to the active vaccine ingredient itself, but to the surrounding chemistry that stabilises it. The approach involves engineering the formulation environment of the vaccine so that the biological compounds remain structurally intact at higher temperatures for longer.
The company's platform is designed to be adaptable: the same stabilisation technology that works for tetanus and diphtheria could potentially be applied to other vaccines, making SPVX02 a proof-of-concept for a much broader pipeline of heat-stable immunisations.
**The Scale of the Problem It Addresses**
Tetanus and diphtheria remain causes of preventable death worldwide. Tetanus — caused by bacteria found in soil, dust, and animal waste — kills approximately **35,000 people per year globally**, with newborn tetanus a particular concern in regions without reliable vaccination programmes. Diphtheria, once largely controlled in wealthy countries, still causes outbreaks in communities where vaccination coverage lapses.
Both diseases are entirely preventable with vaccination. The barrier is not the vaccine — it is getting the vaccine to the people who need it in a condition that works.
A fridge-free tetanus vaccine addresses that barrier directly. It could:
🌍 **Reach remote communities** without electricity or reliable refrigeration infrastructure 🚨 **Be deployed in disaster response** and refugee settings where cold chain maintenance is impossible ✈️ **Simplify long-haul distribution** — no refrigerated transport, no dry ice, no temperature loggers ♻️ **Dramatically reduce waste** — the WHO estimates cold chain failures cause billions of dollars in annual vaccine losses 💉 **Strengthen routine immunisation** in countries where electricity outages routinely compromise existing programmes
**Supported by the UK Innovation Ecosystem**
The SPVX02 programme has been supported by **Innovate UK** — the UK government's innovation agency — and the **National Institute for Health and Care Research (NIHR) Southampton Clinical Research Facility**. It is an example of public funding and regulatory expertise combining with a small, focused biotech to address a global health problem that larger pharmaceutical companies have historically deprioritised.
**Dr Bassam Hallis OBE**, Deputy Director of UKHSA's Vaccine Development and Evaluation Centre, described the programme as "an excellent example of the huge contribution that the UK continues to make to transform public health through innovative technological and scientific advances."
**What Next**
With Phase 1 completed and Phase 2 now in planning, SPVX02 is moving through the clinical pipeline. If Phase 2 confirms immunological non-inferiority against the existing licensed vaccine — the key regulatory hurdle — Stablepharma will be positioned to seek regulatory approval for a product that could reshape how vaccines are stored and distributed globally.
Half of the world's vaccines are currently lost before they reach anyone. That doesn't have to be true. 💉🌍
*Sources: UK Health Security Agency (GOV.UK) · Stablepharma Ltd · Innovate UK · NIHR Southampton · WHO (cold chain data) · March 2026*
