Table 1.
Comparison of the Switch From Trivalent Oral Polio Vaccine (tOPV) to Bivalent OPV (bOPV) Versus the Full Withdrawal of OPVs
| Comparison | Switch From tOPV to bOPV | Full Withdrawal of OPVs |
| Reason for change | End of transmission of type 2 wild polioviruses made the risks from continued regular use of OPV containing type 2 Sabin strain polioviruses outweigh the benefits | End of transmission of all 3 types of wild polioviruses will make the risks from continued regular use of any OPV containing Sabin strain polioviruses outweigh the benefits |
| Synchronization | All countries using tOPV needed to withdraw all tOPV in a synchronized manner within a short time frame to avoid creating type 2 cVDPVs | All countries using OPV will need to withdraw all OPV in a synchronized manner within a short time frame to avoid creating cVDPVs |
| Potential risks from incomplete withdrawal of vaccine | tOPV left in the cold chain and used long after the switch could potentially result in new cVDPVs | OPV left in the cold chain and used long after full OPV withdrawal could potentially result in new cVDPVs |
| OPV use in routine immunization after event | Routine immunization programs used bOPV instead of tOPV after the switch | No OPV should be used in routine immunization programs after full OPV withdrawal |
| Introduction of new form of OPV during event | bOPV was introduced simultaneously with the withdrawal of tOPV during the switch | No new form of OPV will be introduced during full OPV withdrawal |
| Availability of OPV stockpile | Monovalent OPV stockpile available for use in response to polio outbreaks caused by type 2 polioviruses after the switch | Monovalent OPV stockpiles will be available for use in response to polio outbreaks caused by any type of poliovirus after OPV withdrawal |
| Outbreak response resources | Extensive resources available for organizing responses to polio outbreaks caused by cVDPVs after the switch | Fewer resources may be available for organizing responses to polio outbreaks caused by cVDPVs after full OPV withdrawal |
Abbreviation: cVDPV, circulating vaccine-derived poliovirus.