Polio was eradicated in the United States by 1979, thanks to a vaccine. But during its height in the 1950s, the disease affected 58,000 people per year, mostly children. Today, Americans don’t really think too much about polio anymore; though a polio-like virus is currently causing some concern. Since its peak, the global health community has done an admirable job of wiping out polio in much of the rest of the world, pushing the infectious disease to the brink of total eradication.
Getting rid of the last remaining pockets of the disease has proven difficult, mainly because the vaccine against the disease requires refrigeration, which is unavailable in some of the world’s most remote and poorest regions. But Roni Dengler at Discover reports that researchers recently learned how to freeze-dry the vaccine, giving hope that polio’s days are numbered.
In 1988, the World Health Organization created the Global Polio Eradication Initiative to stop the disease once and for all. Since then, incidences of polio worldwide went down 99.9 percent, according to the initiative website. But that final 0.1 percent has proved tricky to beat. Helen Branswell at Stat reports that “each year for the last few years,” the initiative has held out hope for the end of polio would come in that given year. Last year, for instance, just 22 cases were reported. But every time the disease seems to be on the brink of extinction, new outbreaks pop up. In 2016, it re-emerged in Nigeria after two years without a case. Syria had a large outbreak as well. This year, the disease appears to be spreading in Pakistan and Afghanistan.
Nicola Davis at The Guardian reports one problem with the current eradication initiative is the type of vaccine used. The oral vaccine uses a tiny bit of weakened live virus that is not harmful to the vaccinated patient. However, all children in the area must be vaccinated all at once, or else the live virus from the vaccine can be transmitted to unvaccinated children, gain strength and spread, which seems to be the case with the Syria outbreak. To fix that problem, health workers have begun to use inactivated poliovirus (IPV), an injection of dead strains of the virus. The problem is, those vaccines need constant refrigeration, meaning they may not make it to the areas that need them the most.
That’s why Jae Jung, an immunologist at the Keck School of Medicine at the University of Southern California, and Byeong S. Chang, CEO of Integrity Bio, decided to use their expertise to create a shelf-stable version of the vaccine. While researchers had previously used freeze-drying to create stable versions of vaccines against measles and typhoid, the same techniques did not yet work on the IPV.
So, the researchers and their teams used a combination of two new techniques, liquid chromatography and high-throughput screening, to find additives that could be used during the freeze-drying process to stabilize the IPV. Eventually, they found the right formula using magnesium sulphate, an amino acid called histidine, and the sugar, alcohol mannitol. During tests, they stored the vaccine at 98.6 degrees for four weeks before using it to vaccinate mice against polio, finding their freeze-dried version protected the mice just as well as the regular vaccine. The research appears in the journal mBio.
“Stabilization is not rocket science, so most academics don’t pay much attention to this field,” lead author Woo-Jin Shin, also of USC, says in a press release. “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.”
The goal is to eventually test the compound on humans and create a vaccine that can be shelf stable for three months to a year, reports Davis. And that is crucial in reaching the remaining populations of children that have not been vaccinated. Branswell at Stat reports health officials are optimistic that they can reach the 100,000 children in out-of-reach areas in Nigeria.
The situation in Afghanistan and Pakistan, however, is different, with pockets of unvaccinated children and incidences of the disease in areas where it is not safe for outsiders to travel. Aid work in the area was made even more difficult about a decade ago when the CIA used phony vaccination workers to collect DNA from local children during the hunt for Osama bin Laden in Pakistan. That led to a distrust of health professionals in the region and eventually caused the murder of nine vaccine workers. It is believed the stunt set polio eradication in the region back by decades.