In 2001, highly evolved type 1 circulating vaccine-derived poliovirus (cVDPV) was isolated from three acute flaccid paralysis patients and one contact from three separate communities in the Philippines. Complete genomic sequencing of these four cVDPV isolates revealed that the capsid region was derived from the Sabin 1 vaccine strain but most of the noncapsid region was derived from an unidentified enterovirus unrelated to the oral poliovirus vaccine (OPV) strains. The sequences of the cVDPV isolates were closely related to each other, and the isolates had a common recombination site. Most of the genetic and biological properties of the cVDPV isolates were indistinguishable from those of wild polioviruses. However, the most recently identified cVDPV isolate from a healthy contact retained the temperature sensitivity and partial attenuation phenotypes. The sequence relationships among the isolates and Sabin 1 suggested that cVDPV originated from an OPV dose given in 1998 to 1999 and that cVDPV circulated along a narrow chain of transmission. Immunization with the oral poliovirus vaccine (OPV) is the cornerstone of the World Health Organization's program for the global eradication of poliomyelitis (15,44,55,56,65). The attenuated OPV strains of the three poliovirus serotypes (Sabin 1, 2, and 3) replicate in the gut of OPV recipients and can efficiently induce type-specific humoral and mucosal immunity (55), mimicking natural infection. However, replication of OPV in humans is frequently accompanied by genetic change of the vaccine virus, including reversion of key attenuating mutations (5,42

In 2016, the Immunization Technical Advisory Group of the South-East Asia Region (SEAR) endorsed a regional goal to achieve ≤1% prevalence of hepatitis B surface antigen (HBsAg) among 5-year-old children by 2020. Chronic hepatitis B virus (HBV) infection is largely preventable with a birth dose of hepatitis B vaccine (HepB-BD) followed by two to three additional doses. We reviewed the progress towards hepatitis B control through vaccination in SEAR during 1992-2015. We summarized hepatitis B vaccination data and reviewed the literature to determine the prevalence of chronic HBV infection pre- and post-vaccine introduction. We used a mathematical model to determine post-vaccine prevalence of HBsAg among 5 year olds in countries lacking national serosurvey data and estimated the impact of vaccination on disease burden. Regional coverage with three doses of hepatitis B vaccine (HepB3) increased from 56% in 2011 to 87% in 2015. By 2016, 7 of 11 countries had introduced universal HepB-BD. Regional HepB-BD coverage increased from 9% in 2011 to 34% in 2015. In 2015, estimated HBsAg among 5 year olds was 1.1% with variability among countries. Myanmar (3.8%), Timor-Leste (2.7%), Indonesia (1.8%), and India (1%) had the highest prevalence of HBsAg. During 1992-2015, vaccination prevented approximately 16 million chronic HBV infections and 2.6 million related deaths. In 2015, around 197,640 perinatal HBV infections occurred in SEAR with majority occurring in India (62%), Bangladesh (24%), and Myanmar (8%). Myanmar had the highest rate of perinatal chronic HBV infections at 16 per 1000 live births. Despite significant progress in the control of HBV, SEAR needs to secure political commitment for elimination and consider additional strategies, such as promoting health facility births, universal birth dose administration, developing strong coordination between health sectors, and using alternative vaccine delivery methods, to improve HepB-BD coverage and subsequently achieve HBV control and elimination.

In 1988, the World Health Assembly resolved to eradicate poliomyelitis by the year 2000. Although substantial progress was achieved by 2000, global polio eradication proved elusive. In India, the goal was accomplished in 2011, and the entire South-East Asia Region was certified as polio-free in 2014. The year 2016 marks the lowest wild poliovirus type 1 case count ever, the lowest number of polio-endemic countries (Afghanistan, Nigeria and Pakistan), the maintenance of wild poliovirus type 2 eradication, and the continued absence of wild poliovirus type 3 detection since 2012. The year also marks the Global Polio Eradication Initiative (GPEI) moving into the post-cessation of Sabin type 2, after the effort of globally synchronized withdrawal of Sabin type 2 poliovirus in April 2016. Sustained efforts will be needed to ensure polio eradication is accomplished, to overcome the access and security issues, and continue to improve the quality and reach of field operations. After that, surveillance (the “eyes and ears”) will move further to the center stage. Sensitive surveillance will monitor the withdrawal of all Sabin polioviruses, and with facility containment, constitute the cornerstones for eventual global certification of wild poliovirus eradication. An emergency response capacity is essential to institute timely control measures should polio still re-emerge. Simultaneously, the public health community needs to determine whether and how to apply the polio-funded infrastructure to other priorities (after the GPEI funding has stopped). Eradication is the primary goal, but securing eradication will require continued efforts, dedicated resources, and a firm commitment by the global public health community.

While global polio eradication requires tremendous efforts in countries where wild polioviruses (WPVs) circulate, numerous outbreaks have occurred following WPV importation into previously polio-free countries. Countries that have interrupted endemic WPV transmission should continue to conduct routine risk assessments and implement mitigation activities to maintain their polio-free status as long as wild poliovirus circulates anywhere in the world. This article reviews the methods used by World Health Organization (WHO) regional offices to qualitatively assess risk of WPV outbreaks following an importation. We describe the strengths and weaknesses of various risk assessment approaches, and opportunities to harmonize approaches. These qualitative assessments broadly categorize risk as high, medium, or low using available national information related to susceptibility, the ability to rapidly detect WPV, and other population or program factors that influence transmission, which the regions characterize using polio vaccination coverage, surveillance data, and other indicators (e.g., sanitation), respectively. Data quality and adequacy represent a challenge in all regions. WHO regions differ with respect to the methods, processes, cut-off values, and weighting used, which limits comparisons of risk assessment results among regions. Ongoing evaluation of indicators within regions and further harmonization of methods between regions are needed to effectively plan risk mitigation activities in a setting of finite resources for funding and continued WPV circulation.

Region, one of the six regions of World Health Organization, consists of 11 countries with a total population of approximately 2 billion, including Bangladesh,

On 29 October 2000, the World Health Organization (WHO) Regional Commission for the Certification of Poliomyelitis Eradication in the Western Pacific certified the WHO Western Pacific Region as free of indigenous wild poliovirus. This status has been maintained to date: wild poliovirus importations into Singapore (in 2006) and Australia (in 2007) did not lead to secondary cases, and an outbreak in China (in 2011) was rapidly controlled. Circulation of vaccine derived polioviruses in Cambodia, China and the Philippines was quickly interrupted. A robust acute flaccid paralysis surveillance system, including a multitiered polio laboratory network, has been maintained, forming the platform for integrating measles, neonatal tetanus, and other vaccine-preventable disease surveillance and their respective control goals. While polio elimination remains one of the most important achievements in public health in the Western Pacific Region, extended delays in global eradication have, however, led to shifting and competing public health priorities among member states and partners and have made the region increasingly vulnerable.

In 2012, the World Health Organization Regional Committee for the Western Pacific Region (WPR) reaffirmed its commitment to eliminate measles and urged WPR member states to interrupt endemic measles virus transmission as rapidly as possible. In 2013, a large measles outbreak occurred in the Philippines despite implementation of measles elimination strategies including a nationwide supplemental immunization activity (SIA) in 2011 using measles- and rubella-containing vaccine and targeting children aged nine months to seven years. To prevent future measles outbreaks a new tool was developed to assess district-level risk for measles outbreaks, based on the WPR polio risk assessment tool previously applied in the Philippines. Risk was assessed as a function of combined indicator scores from four data input categories: population immunity, surveillance quality, program performance, and threat assessment. On the basis of the overall score, the tool assigned each district a risk category of low, medium, high, or very high. Of the 122 districts and highly urbanized cities in the Philippines, 58 (48%) were classified as high risk or very high risk, including the district of the Metro Manila area and Region 4A where the outbreak began in 2013. Risk assessment results were used to guide the monitoring and supervision during the nationwide SIA conducted in 2014. The initial tool drafted in the Philippines served as a template for development of the global risk assessment tool. Regular annual measles programmatic risk assessments can be used to help plan risk mitigation activities and measure progress toward measles elimination.

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