Creating safer polio vaccine strains for the post-eradication era

While the goal of polio virus eradication is in sight, there are concerns about post-eradication manufacturing and stockpiling vaccine stores containing live virus that could escape and repopulate the environment. A study published on December 31st in PLOS Pathogens reports the generation of new vaccine strains that appear both effective and unable to cause disease after accidental or intended release. Different types of polio vaccines currently exist, but none are optimal from a safety point of view. Live attenuated (weakened) vaccine strains carry genetic mutations that prevent them from causing disease, but they can–in rare cases–revert to more dangerous (or virulent) virus. There are also examples in which live attenuated virus can survive in the gut of immune-compromised individuals and can be shed into the environment through their feces. Inactivated vaccines are themselves safe, but their production at present involves growing large amounts of wild-type (i.e., active virulent) virus that is...