HUMAN TRIALS of the first ‘fridge-free’ vaccines that could reduce waste and barriers to global vaccine deployment have been successful.
Findings from a phase I trial for the SPVX02 tetanus-diphtheria booster jab show the formula, which uses StablevaX technology, remains viable and effective for at least 24 months at temperatures of up to 30°C.
Currently, most vaccines require constant refrigeration or temperature control until use, which creates barriers for health care professionals attempting to distribute vaccines to populations in hot climates, remote locations, or with limited resources.
Vaccines can be damaged if exposed to excessive heat or freezing temperatures, creating additional costs, logistical hurdles, and the risk of doses being wasted.
The dependence on this continuous network of refrigerated storage and transport, known as ‘cold chain’, that is required to keep vaccines stable remains a major challenge for immunisation programmes worldwide.
Many immunisation efforts in low– and middle-income countries face difficulties transporting and storing vaccines because of limited electricity supplies, unreliable infrastructure, and challenging geographical conditions.
A room-temperature stable vaccine could allow healthcare workers to reach more people without depending on complex refrigeration systems.
The phase I clinical trial assessed the safety, tolerability, and immune response generated by SPVX02, a reformulated version of an already existing tetanus-diphtheria booster vaccine.
The randomised trial involved healthy adult participants who received either the SPVX02 vaccine or established comparator vaccines.
Researchers found that candidates who received the ‘fridge-free’ dose produced immune responses comparable to existing approved vaccines whilst no serious adverse reactions or events occurred.
The only notable side effects were comparable to those observed with currently available tetanus-diphtheria booster vaccines. These included pain on the injection site, headaches and chills among other minor symptoms in the period after administration.
Researchers also argue that removing the need for refrigeration could help prevent the current huge levels of vaccine wastage. The World Health Organization estimates that a up to 50% of unused vaccines are disposed of globally every year.
While there are several reasons for why a vaccine may be thrown out before it is given to a patient, including expiration dates and damage, a major cause is failures in the cold chain.
Separate data from the study shows the components of the new vaccine formula also survived cycling between temperatures of -20°C and +40°C.
This could allow the vaccine to be transported between extremely cold and hot climates in quick succession, such as from an aircraft hold to the back of a truck in the heat.
Researchers are confident that the same stabilisation technology could potentially be applied to other vaccines and biological products.
Although the phase I findings provide early evidence that SPVX02 is safe and capable of generating an immune response, larger clinical trials will be needed before the vaccine or technology can be approved for widespread use.
Phase II and phase III trials are already planned, and further research will investigate temperature stability at even higher temperatures, as well as technology application to other vaccines and biological products.
If successful, the technology could represent a major shift in vaccine distribution and immunisation efforts globally.
Reed T 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;DOI:10.1016/j.eclinm.2026.104116
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