Which polio vaccine strategy, Salk's injected inactivated vaccine or Sabin's live oral vaccine, better serves eradication?
The oral vaccine is cheaper, easier to administer and induces stronger intestinal immunity that blocks transmission, which made it the workhorse of the global eradication campaign; but its live virus can, rarely, revert to a form that causes circulating vaccine-derived poliovirus (cVDPV) outbreaks, 721 cases of which were reported worldwide between January 2005 and May 2016, 94 percent of them from the vaccine's own type 2 component. The injected inactivated vaccine carries no such reversion risk but is costlier, requires trained staff to administer, and confers weaker intestinal immunity. The World Health Organization coordinated a global, synchronized switch from trivalent to bivalent oral vaccine in April 2016 specifically to retire the type 2 oral component, introducing injected vaccine into routine schedules worldwide to cover the resulting gap, a policy tradeoff public health authorities continue to weigh as wild poliovirus nears eradication in the remaining endemic countries.
What would resolve this Sustained, verified interruption of all wild and vaccine-derived poliovirus transmission worldwide following a specific vaccine strategy, or a WHO Strategic Advisory Group of Experts consensus settling the remaining oral-to-inactivated transition timeline.
Public Health and EpidemiologyCDC MMWR: Introduction of Inactivated Poliovirus Vaccine and Switch from Trivalent to Bivalent Oral Poliovirus Vaccine