Fridge-Free Vaccines Successfully Tested in Human Trials

Vaccines that do not need to be kept cool in a fridge have been successfully trialled in patients for the first time, say UK scientists. Currently, most vaccines need to be refrigerated or frozen — but around half are wasted each year, mainly because they become unusable after getting too hot or too cold.

In the trial, which involved 60 volunteers, company Stablepharma converted a liquid tetanus-diphtheria vaccine into a "fridge-free" version by keeping it as a dry powder for a year at room temperature before mixing it with water and injecting it.

Vaccines often need strict temperature control during storage and transportation, from the moment of manufacture up until being injected into a patient's arm. This practice is known as the "cold chain" and is especially challenging in the poorest and most remote parts of the world or in war zones, where fridges may be scarce and electricity unreliable.

The new technology is inspired by resurrection plants, which dry out and appear dead during a drought, before springing back to life when it rains. These plants produce large amounts of a sugar called trehalose, which stabilizes the plant's cells during a drought. The trial dried out the tetanus-diphtheria vaccine with trehalose to protect its vital components.

Prof Saul Faust, director of the NIHR Clinical Research Facility in Southampton, said the fridge-free vaccine gave "equivalent" immune responses to the conventional vaccine and was "safe and well tolerated" in the early stage studies. "This obviously has potential to remove cold chain dependence, reduce wastage and improve access," he added.

A larger trial involving 160 people is already due to start in the coming months. This would be the final stage of research, as the original vaccine is already approved and licensed, so there is no requirement to perform the large-scale trials needed for a novel vaccine.