With only 74 cases of polio reported worldwide in 2015, the disease is well on its way to eradication. But re-emergence through accidental release from a biocontainment factory is a small but real risk.
So researchers have developed a strain of poliovirus to use in a new generation of vaccine that could help stamp out the disease once and for all.
The so-called cold-adapted strain is noninfectious, so there would be no outbreak if the poliomyelitis pathogen were ever to escape from a plant.
In the journal PLOS Pathogens, investigators led by Dutch scientists report that the cold-adapted vaccine strains can multiply only in temperatures lower than that of the human body.
The cold viral strains contained in the vaccine were genetically engineered so they are able to grow well at 30 degrees Celsius but not at all at 37 degrees, the normal human temperature.
That means if there were an accidental release and a human were to come into contact with the poliovirus, it couldn't grow and multiply inside the person.
Another reason for developing the new vaccine, said Jerome Custers, a senior vaccine scientist at Jannsen Infectious Disease and Vaccines in the Netherlands, is that the stockpile of the current injectable vaccine is low and it's fairly expensive to make.
“So it would be great if you could manufacture this in a lot of countries in the world," Custers said. "And by allowing that, you really need viruses that are safer to work with, so less virulent, not disease-causing.”
Only six Western countries — Canada, the Netherlands, Belgium, Sweden, Switzerland and France — are now licensed to manufacture the vaccine.
But Custers said having a safe polio vaccine strain that’s easily reproducible would bring down the cost of the drug as more countries, such as India, began manufacturing it.