Read original article on New African
UK-based pharmaceutical company Stablepharma is preparing for a pivotal Phase 2b clinical trial of ‘SPVX02’, its thermostable version of an existing tetanus-diphtheria vaccine, following the success of a Phase 1 clinical trial. Unlike conventional vaccines which become unusable after a few hours or days out of the fridge, ‘SPVX02’ is the first aluminium-containing vaccine that can be kept in storage at room temperature, potentially making it easier and cheaper to transport vaccines to places where reliable electricity and transport infrastructure cannot be taken for granted.
“It’s important that vaccines can reach people anywhere in the world, so that they are accessible for everyone,” says Laura Murphy of Stablepharma. Combined with the potential reduction in greenhouse-gas emissions from refrigeration, she argues, the technology could address several problems at once.
The challenge of keeping vaccines cold
For most vaccines, refrigeration does not begin when they arrive at a hospital or clinic. It starts at the point of manufacture and continues throughout transport, storage and final delivery.
“The whole cold chain of logistical events from the moment a vaccine is made, to the moment it’s dosed, has to be documented to ensure that vaccines have been kept at controlled refrigerated temperatures for the whole duration,” Karen O’Hanlon, Stablepharma’s Chief Operating Officer told me. “It’s not enough just to say a vaccine feels cold, it has to be documented and validated as being stored at a refrigerated cold temperature.”
Vaccines are typically transferred from refrigerated manufacturing facilities into temperature-controlled trucks, warehouses and aircraft before reaching another cold-storage facility at their clinical destination. Maintaining that cold chain requires energy and specialist equipment for monitoring and packaging. Failure in this so-called ‘cold chain’ leads to 50% of vaccines being wasted annually, according to the World Health Organisation. “Obviously, those vaccines must be replaced by the manufacturers who make them, which is a waste. So, it’s not just about the ones that have been lost, it’s the reproduction of the ones that have already been produced and put into the cold chain that then failed – and that’s a big cost globally to the environment and healthcare organisations, but also the end user, from a procurement point of view,” Laura Murphy explains.
Below: Karen O’Hanlon, Chief Operating Officer, Stablepharma.
Turning an existing vaccine into a thermostable one
Stablepharma, founded in 2012, is not developing an entirely new vaccine. Instead, its technology is designed to reformulate existing vaccines, small molecules and biologics so that they remain stable without refrigeration. The new technology uses their proprietary StablevaX technology, where a sugar called ‘trehalose’ – naturally found in resurrection plants, which seem dead during a drought and revitalise during rain – is added to the existing vaccine along with other excipients to produce a thermostable formulation.
“We take the original, existing medicine or vaccine product; we reformulate it with trehalose and other excipients, then freeze-dry it. Our SPVX02 tetanus-diphtheria fridge-free vaccine is presented as a little glass vial with white powder in the bottom that we can reconstitute with sterile water, before administering the vaccine to a patient. So, we don’t really have any massive impact on the manufacturing process – we don’t change the original processes, we simply add to them. There’s no change in the safety or efficacy or immunogenicity of the fridge-free product, everything stays the same as it was in the original product. And that’s kind of the beauty of the work that we do,” explains O’Hanlon.
Stablepharma says its reformulated SPVX02 tetanus-diphtheria vaccine can be stored and transported at room temperature (up to 30°C) without the conventional refrigerated cold chain. Results from the company’s first clinical trial showed that the reformulated vaccine remained comparable with the refrigerated original even after extended storage at 30°C for 24 months.
“What we’ve shown is that the vaccine, even after being stored on a shelf for two years at 30 degrees, is the same as the original product that’s kept in the fridge,” she says.
If the Phase 2b clinical trial and subsequent regulatory reviews confirm these results, the implications could extend well beyond tetanus and diphtheria. Stablepharma’s wider ambition is to apply the same process to other temperature-sensitive pharmaceutical products, especially vaccines.
Immunisation issues in Africa
Cold-chain and refrigeration problems are particularly significant where immunisation systems are already under pressure. Across Africa, more than 30m children each year suffer from ‘vaccine-preventable diseases’, and Africa CDC continues to report major outbreaks of illnesses, including measles and diphtheria across the continent.
Reaching children who have missed routine vaccination is a central aim of the World Health Organization’s Immunization Agenda 2030. Of particular concern are “zero-dose” children, who have not received even the first dose of a diphtheria, tetanus and pertussis (DTP) vaccine. Around 40% of zero-dose and under-immunised children live in conflict-affected settings, where basic health services are difficult to deliver.
This is particularly relevant to SPVX02, Stablepharma’s tetanus-diphtheria approach. Although around 84% of infants globally receive three DTP doses, more than half of the world’s zero-dose children are concentrated in nine countries, including Nigeria, the DRC, Ethiopia and Angola. WHO estimates that Nigeria alone had 2.3m zero-dose children in 2022.
Low immunisation coverage often overlaps with conflict, displacement and institutional fragility. Across the Sahel, insecurity, poverty and climate pressures have weakened health systems. In rural and conflict-affected areas, poor roads and unreliable electricity make continuous vaccine refrigeration difficult, adding another burden for organisations already struggling to deliver food, medicine and basic care.
Logistics are only part of the problem. Immunisation also depends on public confidence and access to services. The 2003 polio vaccine boycott in northern Nigeria showed how vaccination can become entangled with political tensions and distrust.
Africa’s uneven coverage therefore reflects difficult terrain, weak infrastructure, workforce shortages, mistrust and misinformation. A thermostable vaccine cannot resolve conflict, repair roads or rebuild trust. It could, however, remove one of the most technically demanding constraints. Eliminating continuous refrigeration could make reaching remote and underserved communities simpler, cheaper, and more accessible.
A climate argument as well as a health one
Removing refrigeration could also reduce the environmental footprint of vaccination, a crucial factor during a time of climate change and global warming. According to ‘Health Care Without Harm’, an international NGO, healthcare’s climate footprint is equivalent to 4.4% of global net emissions – or, if the health sector was a country, it would be the fifth-largest emitter of greenhouse gas emissions on the planet.
For Stablepharma, this makes thermostability both a public health and sustainability issue.
The ideal model, particularly in Africa, would be a self-sufficient in-country production, “and then it’s just distribution in a truck and storage in any location, even in a box on a shelf, without any requirements for refrigeration”. In-country manufacturing would be possible, O’Hanlon explains, because the manufacturing process uses very standard and readily available manufacturing techniques.
What happens next?
Given that Stablepharma is currently moving through further clinical and regulatory work on SPVX02, the product is not yet ready for routine use. The company is reformulating an already established vaccine, so it has a shorter regulatory pathway than would be required for a completely new vaccine – but it will still be a couple of years before SPVX02 reaches the market.
For SPVX02, the company chose to carry out an initial Phase 1 clinical study before progressing to a larger Phase 2b clinical trial, but future products using the same technology could potentially move directly into the later-stage clinical study required by regulators.
And regulatory approval is only one part of the challenge. For the technology to improve vaccine access in African countries, manufacturers, governments and international health organisations would need to determine how it fits into existing immunisation programmes, how much it costs, where it should be produced and which communities would benefit most.
Thermostability cannot solve mistrust, shortages of healthcare workers or weak health systems. Nor can it remove every logistical obstacle to reaching remote populations. But it could remove one important constraint.
For more than a century, refrigeration has helped make modern vaccination possible. It has also shaped where vaccines can travel, how they must be stored and how much infrastructure is needed to deliver them safely.
If vaccines such as SPVX02 ultimately prove that the refrigerator is no longer essential, the consequences could extend far beyond a single tetanus-diphtheria product, helping to tackle some of Africa’s other significant immunisation challenges.