Novel freeze-dried polio vaccine can be stored without refrigeration

Scientists have developed a freeze-dried polio vaccine that can be stored for weeks without refrigeration, allowing the drug to be transported to remote areas all over the world to completely eradicate the infectious disease.

The injectable vaccine, kept at room temperature for four weeks and then rehydrated, offered full protection against the polio virus when tested in mice, researchers said.

"Stabilisation is not rocket science, so most academics don't pay much attention to this field," said Woo-Jin Shin, from University of Southern California in the US.

"However, no matter how wonderful a drug or vaccine is, if it isn't stable enough to be transported, it doesn't do anyone much good," said Shin.

Polio is on the brink of complete eradication, with just 22 reported cases worldwide in 2017. The highly infectious disease, which causes lifelong paralysis and disability mostly in young children, is a fading memory in many places. Yet in countries where vaccination rates are spotty, young children are at risk.

The biggest hitch to complete eradication has been creating a temperature-stable vaccine for use in developing countries where refrigeration may be unavailable.

Recent polio cases have been reported in Nigeria, Papua New Guinea, Syria and Pakistan.

By removing moisture through freeze-drying, researchers have created temperature-stable vaccines for measles, typhoid and meningococcal disease.

However, scientists have not been able to make a polio vaccine that retains potency through freeze-drying and rehydration.

Researchers used two lab techniques -- liquid chromatography and high-throughput screening -- that allowed them to analyse a high volume of ingredients and formulations until they found one that worked.