Polio, a disease that once paralyzed over 350,000 people around the world, has dropped to just about 407 cases in 2013 due to Polio vaccine, as reported by Centers for Disease Control and Prevention. Although the disease is on the brink of eradication with only 22 reported cases in 2017 worldwide, it still lurks in many countries as storage and transportation of the vaccine require refrigeration.
A team of researchers at the University of Southern California (USC) have been able to develop a polio vaccine that doesn’t need refrigeration, suggesting it could someday be used worldwide to completely eradicate the disease. The researchers freeze dried the injectable vaccine into a powder, stored it in room temperature for four weeks, and they rehydrated. When tested in mice model, the powdered form offered full protection against the polio virus.
The study’s first author Woo-Jin Shin said that many academics often neglect the importance of stabilization, but regardless of how effective a vaccine or drug is, if it is unstable to be transported, it doesn’t do much good to anyone.
The study is detailed in the recent issue of the journal mBio. Polio is one of the highly infectious diseases causing disability and lifelong paralysis, mostly in young children. It may be a fading memory in several places, but in countries where vaccination rate is extremely low, children are still at risk.
Storage of the vaccine relies on keeping it cold but refrigeration may not be reliable or available in various developing countries. So the polio virus still has strongholds in Papua New Guinea, Pakistan, Nigeria, and Syria.
In the US, the polio epidemic peaked during 1950s. With mass immunization, reported cases of polio reduced from 58,000 to 5,600 in 1957, and no cases of polio have been generated in the country since 1979.
The freeze-drying process to remove moisture have been widely used to make temperature-stable vaccines for many diseases including typhoid, measles, and meningococcal disease. However, scientists were unable to create polio vaccine that retain its potency through freeze-drying and rehydration.
In the new study, the scientists used two lab techniques – liquid chromatography and high-throughput screening. These methods enabled them to evaluate large amount of ingredients and formulations to find the one that works. The moisture content of the winning formulation was just 0.77% which could eliminate the need for cold storage and deliver a final blow to the disease.