Fridge-Free Vaccines Successfully Trialled for First Time in Patients

Scientists in the United Kingdom have successfully tested a new generation of vaccines that require no refrigeration, marking the first time such technology has been trialled directly in patients. Researchers from pharmaceutical company Stablepharma converted a standard liquid tetanus-diphtheria vaccine into a dry powder formulation using a sugar called trehalose, keeping it stable at room temperature for an entire year before mixing it with water and administering it to volunteers.

The Cold Chain Problem

Currently, most vaccines worldwide must be kept within a strict temperature range from manufacturing through to the point of injection, a logistical challenge known as the cold chain. Around half of all vaccines produced globally are wasted each year, mainly because they become unusable after exposure to temperatures that are too hot or too cold. This problem is particularly acute in remote and low-income regions, as well as in conflict zones where consistent electricity and refrigeration are scarce.

The new approach draws inspiration from a remarkable plant. Certain desert plants known as resurrection plants survive severe drought by producing large quantities of trehalose, a sugar that stabilises the plant's cellular structures in the absence of water. Stablepharma applied the same principle to the vaccine, drying it with trehalose to protect its active components without the need for cold storage.

Promising Results in Patients

The trial enrolled 60 healthy volunteers. Professor Saul Faust, director of the NIHR Clinical Research Facility at Southampton, reported that the fridge-free version produced "equivalent" immune responses to the conventional refrigerated vaccine and was "safe and well tolerated" in the early-stage study. A larger trial involving 160 participants is expected to begin within the coming months.

Because the original tetanus-diphtheria vaccine is already approved and licensed, this larger trial will not need to be a full-scale Phase 3 study. Researchers say the vaccine can survive temperature cycling between minus 20 degrees Celsius and plus 40 degrees Celsius, meaning it could remain viable after being transported in a cold aircraft cargo hold and then in a hot truck, without deteriorating.

Global Health Impact

The World Health Organization has set a benchmark of vaccines that can survive at 30 degrees Celsius and 75% relative humidity. The researchers say their data meets this target. If scaled successfully, the technology could transform vaccine programmes in regions where cold chain infrastructure does not exist, potentially saving millions of doses that are currently discarded every year.