The outbreak appears to be over. Now, dozens of epidemiologists are trying to reconstruct what happened. Nevertheless, the recent outbreak has leaders of the global polio eradication campaign worried. The day will come when the world is free of wild polio and WHO will recommend that people stop getting the oral vaccine. Children born from that moment onward will be vulnerable to polio infection.
Research suggests that under ideal conditions, vaccine virus strains die out quickly.
Babies born three months after a Cuban immunization day don't acquire any immunity to the poliovirus until they're vaccinated on the next immunization day. Together, those findings suggest that vaccine strains disappear completely within a few months, provided a population is fully immunized at the moment the last person gets vaccinated. It's clear that the world is going to have to behave like Cuba, and not like Hispaniola, in the polio end-game. Countries need to maintain high levels of immunity even if they haven't had polio for years. They need to have good surveillance, so they can detect another Hispaniola-like outbreak if it occurs.