Toward Establishing Integrated, Comprehensive, and Sustainable Meningitis Surveillance in Africa to Better Inform Vaccination Strategies.

Large populations across sub-Saharan Africa remain at risk of devastating acute bacterial meningitis epidemics and endemic disease. Meningitis surveillance is a cornerstone of disease control, essential for describing temporal changes in disease epidemiology, the rapid detection of outbreaks, guiding vaccine introduction and monitoring vaccine impact. However, meningitis surveillance in most African countries is weak, undermined by parallel surveillance systems with little to no synergy and limited laboratory capacity. African countries need to implement comprehensive meningitis surveillance systems to adapt to the rapidly changing disease trends and vaccine landscapes. The World Health Organization and partners have developed a new investment case to restructure vaccine-preventable disease surveillance. With this new structure, countries will establish comprehensive and sustainable meningitis surveillance systems integrated with greater harmonization between population-based and sentinel surveillance systems. There will also be stronger linkage with existing surveillance systems for vaccine-preventable diseases, such as polio, measles, yellow fever, and rotavirus, as well as with other epidemic-prone diseases to leverage their infrastructure, transport systems, equipment, human resources and funding. The implementation of these concepts is currently being piloted in a few countries in sub-Saharan Africa with support from the World Health Organization and other partners. African countries need to take urgent action to improve synergies and coordination between different surveillance systems to set joint priorities that will inform action to control devastating acute bacterial meningitis effectively.

Global Rotavirus and Pneumococcal Conjugate Vaccine Introductions and the Association With Country Disease Surveillance, 2006-2018.

BACKGROUND: To inform the introduction of pneumococcal conjugate vaccine (PCV) and rotavirus vaccine, the World Health Organization (WHO) established the Global Invasive Bacterial Vaccine-Preventable Disease Surveillance Network (GISN) and the Global Rotavirus Surveillance Network (GRSN) in 2008. We investigated whether participation in these networks or other surveillance was associated with vaccine introduction. METHODS: Between 2006 and 2018, among all WHO member states, we used multivariable models adjusting for economic status to assess (1) the association between surveillance for pneumococcal disease or rotavirus disease, including participation in GISN or GRSN and the introduction of the PCV or the rotavirus vaccine, respectively, and (2) the association between the rotavirus disease burden and the rotavirus vaccine introduction among 56 countries participating in GRSN from 2008 to 2018. RESULTS: Countries that participated in or conducted surveillance for invasive pneumococcal disease or rotavirus disease were 3.5 (95% confidence interval [CI], 1.7-7.1) and 4.2 (95% CI, 2.1-8.6) times more likely to introduce PCV or rotavirus respectively, compared to those without surveillance. Among countries participating in GRSN, there was insufficient evidence to demonstrate an association between countries with higher rotavirus positivity and vaccine introduction. CONCLUSIONS: Surveillance should be incorporated into advocacy strategies to encourage the introduction of vaccines, with countries benefiting from data from, support for, and coordination of international disease surveillance networks.

Gavi Support for Typhoid Conjugate Vaccines: Moving From Global Investments to Country Introduction.

Nine years elapsed between Gavi's investment decision to support typhoid conjugate vaccines (TCVs) in 2008 and Gavi support becoming available for countries to introduce TCV. The protracted path toward Gavi support for TCV highlights the challenges of vaccine development for lower-income countries and the importance of Gavi engagement as early as possible in product development processes to support the alignment of manufacturing, global policy, and program implementation. Early engagement would provide inputs to inform strategic vaccine investment decisions that transition more efficiently toward country implementation. Several countries have been approved for Gavi support to introduce TCV in 2019-2020. The paucity of generalizable typhoid epidemiological data in early introducing countries has reinforced the need for continued evidence generation regarding typhoid epidemiology and TCV impact. This has led to the development of guidance and tools to support country decision making for TCV introduction based on enhanced understanding of local typhoid burden and risk.

Clinical Surveillance and Evaluation of Suspected Ebola Cases in a Vaccine Trial During an Ebola Epidemic: The Sierra Leone Trial to Introduce a Vaccine Against Ebola.

Clinical Trials Registration: ClinicalTrials.gov [NCT02378753] and Pan African Clinical Trials Registry [PACTR201502001037220].

Planning for globally coordinated cessation of bivalent oral poliovirus vaccine: risks of non-synchronous cessation and unauthorized oral poliovirus vaccine use.

BACKGROUND: Oral polio vaccine (OPV) containing attenuated serotype 2 polioviruses was globally withdrawn in 2016, and bivalent OPV (bOPV) containing attenuated serotype 1 and 3 polioviruses needs to be withdrawn after the certification of eradication of all wild polioviruses to eliminate future risks from vaccine-derived polioviruses (VDPVs). To minimize risks from VDPVs, the planning and implementation of bOPV withdrawal should build on the experience with withdrawing OPV containing serotype 2 polioviruses while taking into account similarities and differences between the three poliovirus serotypes. METHODS: We explored the risks from (i) a failure to synchronize OPV cessation and (ii) unauthorized post-cessation OPV use for serotypes 1 and 3 in the context of globally-coordinated future bOPV cessation and compared the results to similar analyses for serotype 2 OPV cessation. RESULTS: While the risks associated with a failure to synchronize cessation and unauthorized post-cessation OPV use appear to be substantially lower for serotype 3 polioviruses than for serotype 2 polioviruses, the risks for serotype 1 appear similar to those for serotype 2. Increasing population immunity to serotype 1 and 3 poliovirus transmission using pre-cessation bOPV supplemental immunization activities and inactivated poliovirus vaccine in routine immunization reduces the risks of circulating VDPVs associated with non-synchronized cessation or unauthorized OPV use. CONCLUSIONS: The Global Polio Eradication Initiative should synchronize global bOPV cessation during a similar window of time as occurred for the global cessation of OPV containing serotype 2 polioviruses and should rigorously verify the absence of bOPV in immunization systems after its cessation.

Modeling Poliovirus Transmission in Pakistan and Afghanistan to Inform Vaccination Strategies in Undervaccinated Subpopulations.

Due to security, access, and programmatic challenges in areas of Pakistan and Afghanistan, both countries continue to sustain indigenous wild poliovirus (WPV) transmission and threaten the success of global polio eradication and oral poliovirus vaccine (OPV) cessation. We fitted an existing differential-equation-based poliovirus transmission and OPV evolution model to Pakistan and Afghanistan using four subpopulations to characterize the well-vaccinated and undervaccinated subpopulations in each country. We explored retrospective and prospective scenarios for using inactivated poliovirus vaccine (IPV) in routine immunization or supplemental immunization activities (SIAs). The undervaccinated subpopulations sustain the circulation of serotype 1 WPV and serotype 2 circulating vaccine-derived poliovirus. We find a moderate impact of past IPV use on polio incidence and population immunity to transmission mainly due to (1) the boosting effect of IPV for individuals with preexisting immunity from a live poliovirus infection and (2) the effect of IPV-only on oropharyngeal transmission for individuals without preexisting immunity from a live poliovirus infection. Future IPV use may similarly yield moderate benefits, particularly if access to undervaccinated subpopulations dramatically improves. However, OPV provides a much greater impact on transmission and the incremental benefit of IPV in addition to OPV remains limited. This study suggests that despite the moderate effect of using IPV in SIAs, using OPV in SIAs remains the most effective means to stop transmission, while limited IPV resources should prioritize IPV use in routine immunization.

Experience With Inactivated Polio Vaccine Introduction and the "Switch" From Trivalent to Bivalent Oral Polio Vaccine in the World Health Organization's Western Pacific Region.

The World Health Organization (WHO) Western Pacific Region (WPR) has maintained its polio-free status since 2000. The emergence of vaccine-derived polioviruses (VDPVs), however, remains a risk, as oral polio vaccine (OPV) is still used in many of the region's countries, and pockets of unimmunized or underimmunized children exist in some countries. From 2014 to 2016, the region participated in the globally coordinated efforts to introduce inactivated polio vaccine (IPV) into all countries that did not yet include it in their national immunization schedules, and to "switch" from trivalent OPV (tOPV) to bivalent OPV (bOPV) in all countries still using OPV in 2016.As of September 2016, 15 of 17 countries and areas that did not use IPV by the end of 2014 had introduced IPV. Introduction in the remaining 2 countries has been delayed because of the global shortage of IPV, making it unavailable to select lower-risk countries until the fourth quarter of 2017. All 16 countries using OPV as of 2016 successfully withdrew tOPV during the globally synchronized switch from April to May 2016, and 15 of 16 countries introduced bOPV at the same time, with the remaining country introducing it within 30 days. While countries were primarily responsible for self-funding these activities, additional support was provided.The main challenges encountered in the Western Pacific Region with both IPV introduction and the tOPV-bOPV switch were related to overcoming regulatory policies and challenges with vaccine procurement. As a result, substantial lead time was needed to resolve procurement and regulatory issues before the introductions of IPV and bOPV. As the global community prepares for the full removal of all OPV from immunization programs, this need for lead time and consideration of the impact on national policies should be considered.

Introduction of Inactivated Polio Vaccine, Withdrawal of Type 2 Oral Polio Vaccine, and Routine Immunization Strengthening in the Eastern Mediterranean Region.

The Global Polio Eradication Initiative has reduced the global incidence of polio by 99% and the number of countries with endemic polio from 125 to 3 countries. The Polio Eradication and Endgame Strategic Plan 2013-2018 (Endgame Plan) was developed to end polio disease. Key elements of the endgame plan include strengthening immunization systems using polio assets, introducing inactivated polio vaccine (IPV), and replacing trivalent oral polio vaccine with bivalent oral polio vaccine ("the switch"). Although coverage in the Eastern Mediterranean Region (EMR) with the third dose of a vaccine containing diphtheria, tetanus, and pertussis antigens (DTP3) was ≥90% in 14 countries in 2015, DTP3 coverage in EMR dropped from 86% in 2010 to 80% in 2015 due to civil disorder in multiple countries. To strengthen their immunization systems, Pakistan, Afghanistan, and Somalia developed draft plans to integrate Polio Eradication Initiative assets, staff, structure, and activities with their Expanded Programmes on Immunization, particularly in high-risk districts and regions. Between 2014 and 2016, 11 EMR countries introduced IPV in their routine immunization program, including all of the countries at highest risk for polio transmission (Afghanistan, Pakistan, Somalia, and Yemen). As a result, by the end of 2016 all EMR countries were using IPV except Egypt, where introduction of IPV was delayed by a global shortage. The switch was successfully implemented in EMR due to the motivation, engagement, and cooperation of immunization staff and decision makers across all national levels. Moreover, the switch succeeded because of the ability of even the immunization systems operating under hardship conditions of conflict to absorb the switch activities.

Resource Needs for the Trivalent Oral Polio to Bivalent Oral Polio Vaccine Switch in Indonesia.

Background: We present an empirical economic cost analysis of the April 2016 switch from trivalent (tOPV) to bivalent (bOPV) oral polio vaccine at the national-level and 3 provinces (Bali, West Sumatera and Nusa Tenggara) for Indonesia's Expanded Program on Immunization. Methods: Data on the quantity and prices of resources used in the 4 World Health Organization guideline phases of the switch were collected at the national-level and in each of the sampled provinces, cities/districts, and health facilities. Costs were calculated as the sum of the value of resources reportedly used in each sampled unit by switch phase. Results: Estimated national-level costs were $46 791. Costs by health system level varied from $9062 to $34 256 at the province-level, from $4576 to $11 936 at the district-level , and from $3488 to $29 175 at the city-level. Estimated national costs ranged from $4 076 446 (Bali, minimum cost scenario) to $28 120 700 (West Sumatera, maximum cost scenario). Conclusions: Our findings suggest that the majority of tPOV to bOPV switch costs were borne at the subnational level. Considerable variation in reported costs among health system levels surveyed indicates a need for flexibility in budgeting for globally synchronized public health activities.

Lessons Learned From the Introduction of Inactivated Poliovirus Vaccine in Bangladesh.

Background: We assessed programmatic adaptations and infants' uptake of inactivated poliovirus vaccine (IPV) after its introduction into the routine immunization schedule in Bangladesh. Methods: Using convenience and probability sampling, we selected 23 health facilities, 36 vaccinators, and 336 caregivers, within 5 districts and 3 city corporations. We collected data during August-October 2015 by conducting interviews, reviewing vaccination records, and observing activities. Results: Knowledge about IPV was high among vaccinators (94%). No problems with IPV storage, transport, or waste disposal were detected, but shortages were reported in 20 health facilities (87%). Wastage per 5-dose vaccine vial was above the recommended 30% in 20 health facilities (87%); all were related to providing <5 doses per open vial. Among eligible infants, 87% and 86% received the third dose of pentavalent and oral poliovirus vaccine, respectively, but only 65% received IPV at the same visit. Among 73 infants not vaccinated with IPV, 58% of caregivers reported that vaccine was unavailable. Conclusions: Bangladesh successfully introduced IPV, but shortages related to insufficient global supply and high vaccine wastage in small outreach immunization sessions might reduce its impact on population immunity. Minimizing wastage and use of a 2-dose fractional-IPV schedule could extend IPV immunization to more children.

Monitoring and Validation of the Global Replacement of tOPV with bOPV, April-May 2016.

The phased withdrawal of oral polio vaccine (OPV) associated with the Polio Eradication and Endgame Strategic Plan 2013-2018 began with the synchronized global replacement of trivalent OPV (tOPV) with bivalent OPV (bOPV) during April - May 2016, a transition referred to as the "switch." The World Health Organization's (WHO) Strategic Advisory Group of Experts (SAGE) on Immunization recommended conducting this synchronized switch in all 155 OPV-using countries and territories (which collectively administered several hundred million doses of tOPV each year via several hundred thousand facilities) to reduce risks of re-emergence of vaccine-derived polioviruses. Safe execution of this switch required implementation of an associated independent monitoring strategy, the primary objective of which was verification that tOPV was no longer available for administration post-switch. This strategy had to be both practical and rigorous such that tOPV withdrawal could be reasonably employed and confirmed in all countries and territories within a discreet timeframe. Following these principles, WHO recommended that designated monitors in each of the 155 countries and territories visit all vaccine stores as well as a 10% sample of highest-risk health facilities within two weeks of the national switch date, removing any tOPV vials found. National governments were required to provide the WHO with formal validation of execution and monitoring of the switch. In practice, all countries reported cessation of tOPV by 12 May 2016 and 95% of countries and territories submitted detailed monitoring data to WHO. According to these data, 272 out of 276 (99%) national stores, 3,741 out of 3.968 (94%) regional stores, 16,144 out of 22,372 (72%) district level stores, and 143,050 out of 595,401 (24%) of health facilities were monitored. These data, along with field reports suggest that monitoring and validation of the switch was efficient and effective, and that the strategies used during the process could be adapted to future stages of OPV withdrawal.

Acceptance of the Administration of Multiple Injectable Vaccines in a Single Immunization Visit in Albania.

Background: Albania introduced inactivated polio vaccine (IPV) into its immunization system in May 2014, increasing the maximum recommended number of injectable vaccines given in a single visit from 2 to 3. Methods: Health-care providers and caregivers were interviewed at 42 health facilities in Albania to assess knowledge, attitudes, and practices regarding injectable vaccine administration. Immunization register data were abstracted from December 2014 to July 2015 at the same facilities to explore the number of injectable vaccines children received during their 2- and 4-month visits. Results: The majority of children (87%) identified in the record review at either their 2- or 4-month immunization visit received all 3 injectable vaccines in a single visit. Almost all children who did not receive the vaccines in a single visit were subsequently fully immunized, most within a 2-week period. Over half of caregivers whose children got 3 or more injectable vaccines in a single visit reported being only comfortable with 1 or 2 injectable vaccines in a single visit. Conclusions: Despite most caregivers expressing hesitation regarding children receiving multiple injectable vaccines in a single visit, most children received vaccines according to the recommended schedule. Almost all children eventually received all recommended vaccines.

Disposing of Excess Vaccines After the Withdrawal of Oral Polio Vaccine.

Until recently, waste management for national immunization programs was limited to sharps waste, empty vaccine vials, or vaccines that had expired or were no longer usable. However, because wild-type 2 poliovirus has been eradicated, the World Health Organization's (WHO's) Strategic Advisory Group of Experts on Immunization deemed that all countries must simultaneously cease use of the type 2 oral polio vaccine and recommended that all countries and territories using oral polio vaccine (OPV) "switch" from trivalent OPV (tOPV; types 1, 2, and 3 polioviruses) to bivalent OPV (bOPV; types 1 and 3 polioviruses) during a 2-week period in April 2016. Use of tOPV after the switch would risk outbreaks of paralysis related to type 2-circulating vaccine-derived poliovirus (cVDPV2). To minimize risk of vaccine-derived polio countries using OPV were asked to dispose of all usable, unexpired tOPV after the switch to bOPV. In this paper, we review the rationale for tOPV disposal and describe the global guidelines provided to countries for the safe and appropriate disposal of tOPV. These guidelines gave countries flexibility in implementing this important task within the confines of their national regulations, capacities, and resources. Steps for appropriate disposal of tOPV included removal of all tOPV vials from the cold chain, placement in appropriate bags or containers, and disposal using a recommended approach (ie, autoclaving, boiling, chemical inactivation, incineration, or encapsulation) followed by burial or transportation to a designated waste facility. This experience with disposal of tOPV highlights the adaptability of national immunization programs to new procedures, and identifies gaps in waste management policies and strategies with regard to disposal of unused vaccines. The experience also provides a framework for future policies and for developing programmatic guidance for the ultimate disposal of all OPV after the eradication of polio.

Financial Support to Eligible Countries for the Switch From Trivalent to Bivalent Oral Polio Vaccine-Lessons Learned.

The global switch from trivalent oral polio vaccine (tOPV) to bivalent oral polio vaccine (bOPV) ("the switch") presented an unprecedented challenge to countries. In order to mitigate the risks associated with country-level delays in implementing the switch, the Global Polio Eradication Initiative provided catalytic financial support to specific countries for operational costs unique to the switch. Between November 2015 and February 2016, a total of approximately US$19.4 million in financial support was provided to 67 countries. On average, country budgets allocated 20% to human resources, 23% to trainings and meetings, 8% to communications and advocacy, 9% to logistics, 15% to monitoring, and 5% to waste management. All 67 funded countries successfully switched from tOPV to bOPV during April-May 2016. This funding provided target countries with the necessary catalytic support to facilitate the execution of the switch on an accelerated timeline, and the mechanism offers a model for similar support to future global health efforts, such as the eventual global withdrawal of bOPV.

Cold-Chain Adaptability During Introduction of Inactivated Polio Vaccine in Bangladesh, 2015.

Background: Introduction of inactivated polio vaccine creates challenges in maintaining the cold chain for vaccine storage and distribution. Methods: We evaluated the cold chain in 23 health facilities and 36 outreach vaccination sessions in 8 districts and cities of Bangladesh, using purposive sampling during August-October 2015. We interviewed immunization and cold-chain staff, assessed equipment, and recorded temperatures during vaccine storage and transportation. Results: All health facilities had functioning refrigerators, and 96% had freezers. Temperature monitors were observed in all refrigerators and freezers but in only 14 of 66 vaccine transporters (21%). Recorders detected temperatures >8°C for >60 minutes in 5 of 23 refrigerators (22%), 3 of 6 cold boxes (50%) transporting vaccines from national to subnational depots, and 8 of 48 vaccine carriers (17%) used in outreach vaccination sites. Temperatures <2°C were detected in 4 of 19 cold boxes (21%) transporting vaccine from subnational depots to health facilities and 14 of 48 vaccine carriers (29%). Conclusions: Bangladesh has substantial cold-chain storage and transportation capacity after inactivated polio vaccine introduction, but temperature fluctuations during vaccine transport could cause vaccine potency loss that could go undetected. Bangladesh and other countries should strive to ensure consistent and sufficient cold-chain storage and monitor the cold chain during vaccine transportation at all levels.

Administering Multiple Injectable Vaccines During a Single Visit-Summary of Findings From the Accelerated Introduction of Inactivated Polio Vaccine Globally.

Background: In 2013, the World Health Organization's (WHO's) Strategic Advisory Group of Experts (SAGE) recommended that all 126 countries using only oral polio vaccine (OPV) introduce at least 1 dose of inactivated polio vaccine (IPV) into their routine immunization schedules by the end of 2015. In many countries, the addition of IPV would necessitate delivery of multiple injectable vaccines (hereafter, "multiple injections") during a single visit, with infants receiving IPV alongside pentavalent vaccine (which covers diphtheria, tetanus, and whole-cell pertussis; hepatitis B; and Haemophilus influenzae type b) and pneumococcal vaccine. Unanticipated concerns emerged from countries over acceptability of multiple injections, sites of administration, and safety. We contextualized the issues surrounding multiple injections by documenting concerns associated with administration of ≥3 injections, existing evidence in the published literature, and findings of a systematic review on administration practices and techniques. Methods: Concerns associated with multiple-injection visits were documented from meetings and personal communications with immunization program managers. Published literature on the acceptability of multiple injections by providers and caregivers was summarized, and a systematic review of the literature on administration practices was completed on the following topics: spacing between injection sites (ie, vaccine spacing), site of injection, route of injection, and procedural preparedness. WHO and United Nations Children's Fund data from 2013-2015 were used to assess multiple-injection visits included in national immunization schedules. Results: Healthcare provider and caregiver attitudes and practices indicated concerns about infant pain, potential adverse effects, and uncertainty about vaccine effectiveness with multiple-injection visits. Published literature reinforced the record of safety and acceptance of the recommended schedule of IPV by the SAGE, but the evidence was largely from developed countries. Parental acceptance of multiple injections was associated with a positive provider recommendation to the caregiver. Findings of the systematic review identified that the intramuscular route is preferred over the subcutaneous route for vaccine administration and that the vastus lateralis muscle is preferred over the deltoid muscle for intramuscular injections. Recommendations on vaccine spacing and procedural preparedness were based on practical necessities, but comparative evidence was not identified. During 2013-2015, 85 countries added IPV to their immunization schedules, 46 (55%) of which adopted a schedule resulting in 3 injectable vaccines being administered in a single visit. Conclusion: The multiple-injection experience identified gaps in guidance for future vaccine introductions. Global partner organizations quickly mobilized to assess, document, and communicate the existing global experience on multiple-injection visits. This evidence-based approach provided reassurance to opinion leaders, health workers, and professional societies, thus encouraging uptake of IPV as a second or third injection in an accelerated manner globally.

Considerations for the Full Global Withdrawal of Oral Polio Vaccine After Eradication of Polio.

Eliminating the risk of polio from vaccine-derived polioviruses is essential for creating a polio-free world, and eliminating that risk will require stopping use of all oral polio vaccines (OPVs) once all types of wild polioviruses have been eradicated. In many ways, the experience with the global switch from trivalent OPV (tOPV) to bivalent OPV (bOPV) can inform the eventual full global withdrawal of OPV. Significant preparation will be needed for a thorough, synchronized, and full withdrawal of OPV, and such preparation would be aided by setting a reasonably firm date for OPV withdrawal as far in advance as possible, ideally at least 24 months. A shorter lead time would provide valuable flexibility for decisions about when to stop use of OPV in the context of uncertainty about whether or not all types of wild polioviruses had been eradicated, but it might increase the cost of OPV withdrawal.

Lessons Learned From Managing the Planning and Implementation of Inactivated Polio Vaccine Introduction in Support of the Polio Endgame.

The Immunization Systems Management Group (IMG) was established as a time-limited entity, responsible for the management and coordination of Objective 2 of the Polio Eradication and Endgame Strategic Plan. This objective called for the introduction of at least 1 dose of inactivated polio vaccine (IPV) into the routine immunization programs of all countries using oral polio vaccine (OPV) only. Despite global vaccine shortages, which limited countries' abilities to access IPV in a timely manner, 105 of 126 countries using OPV only introduced IPV within a 2.5-year period, making it the fastest rollout of a new vaccine in history. This achievement can be attributed to several factors, including the coordination work of the IMG; high-level engagement and advocacy across partners; the strong foundations of the Expanded Programme on Immunization at all levels; Gavi, the Vaccine Alliance's vaccine introduction experiences and mechanisms; innovative approaches; and proactive communications. In many ways, the IMG's work on IPV introduction can serve as a model for other vaccine introductions, especially in an accelerated context.

Implementing the Synchronized Global Switch from Trivalent to Bivalent Oral Polio Vaccines-Lessons Learned From the Global Perspective.

In 2015, the Global Commission for the Certification of Polio Eradication certified the eradication of type 2 wild poliovirus, 1 of 3 wild poliovirus serotypes causing paralytic polio since the beginning of recorded history. This milestone was one of the key criteria prompting the Global Polio Eradication Initiative to begin withdrawal of oral polio vaccines (OPV), beginning with the type 2 component (OPV2), through a globally synchronized initiative in April and May 2016 that called for all OPV using countries and territories to simultaneously switch from use of trivalent OPV (tOPV; containing types 1, 2, and 3 poliovirus) to bivalent OPV (bOPV; containing types 1 and 3 poliovirus), thus withdrawing OPV2. Before the switch, immunization programs globally had been using approximately 2 billion tOPV doses per year to immunize hundreds of millions of children. Thus, the globally synchronized withdrawal of tOPV was an unprecedented achievement in immunization and was part of a crucial strategy for containment of polioviruses. Successful implementation of the switch called for intense global coordination during 2015-2016 on an unprecedented scale among global public health technical agencies and donors, vaccine manufacturers, regulatory agencies, World Health Organization (WHO) and United Nations Children's Fund (UNICEF) regional offices, and national governments. Priority activities included cessation of tOPV production and shipment, national inventories of tOPV, detailed forecasting of tOPV needs, bOPV licensing, scaling up of bOPV production and procurement, developing national operational switch plans, securing funding, establishing oversight and implementation committees and teams, training logisticians and health workers, fostering advocacy and communications, establishing monitoring and validation structures, and implementing waste management strategies. The WHO received confirmation that, by mid May 2016, all 155 countries and territories that had used OPV in 2015 had successfully withdrawn OPV2 by ceasing use of tOPV in their national immunization programs. This article provides an overview of the global efforts and challenges in successfully implementing this unprecedented global initiative, including (1) coordination and tracking of key global planning milestones, (2) guidance facilitating development of country specific plans, (3) challenges for planning and implementing the switch at the global level, and (4) best practices and lessons learned in meeting aggressive switch timelines. Lessons from this monumental public health achievement by countries and partners will likely be drawn upon when bOPV is withdrawn after polio eradication but also could be relevant for other global health initiatives with similarly complex mandates and accelerated timelines.