Seroprevalence of poliovirus antibodies in Nigeria: refining strategies to sustain the eradication effort.

Introduction: in 2016, a switch from trivalent oral poliovirus vaccine (OPV) (containing serotypes 1,2,3) to bivalent OPV (types 1,3) was implemented globally. We assessed the seroprevalence of poliovirus antibody levels in selected Nigerian states, before and after the switch, documented poliovirus type2 outbreak responses conducted and ascertained factors associated with immunity gaps based on seroprevalence rates. Methods: we conducted a secondary analysis of stored serum samples from the 2018 Nigeria National HIV/AIDS Indicator and Impact Survey. Serum from 1,185 children aged 0-119 months residing in one southern and four northern states were tested for serotype-specific PV neutralizing antibodies; seropositivity was a reciprocal titer ≥8. We conducted regression analysis to determine sociodemographic risk factors associated with low seroprevalence using SAS 9.4. Results: children aged 24-119 months (pre-switch cohort) had seroprevalence against PV1, PV2, and PV3, of 97.3% (95% CI:96.4-98.2), 93.8% (95% CI:92.2-95.5), and 91.3% (95% CI:89.2-93.4), while children aged <24 months (post-switch) had seroprevalence of 86.0% (95% CI:81.2-90.8), 55.6% (95% CI: 47.7-63.4), and 77.2% (95% CI:71.0-83.4) respectively. Regression analysis showed age <24 months was associated with lower seroprevalence against all PV serotypes, (p<0.0001); females had lower seroprevalence against PV1 (p=0.0184) and PV2 (p=0.0354); northern states lower seroprevalence against PV1 (p=0.0039), while well-water source lower seroprevalence against PV3 (p=0.0288). Conclusion: this study showed high seroprevalence rates against PV 1, 2, and 3 in pre-switch children (aged 24-119 months). However, post-switch children (<24 months) had low immunity against PV2 despite outbreak responses. Strategies to increase routine immunization coverage and high-quality polio campaigns can increase immunity against polio virus.

Progress Toward Poliomyelitis Eradication - Nigeria, January 2018-May 2019.

The number of wild poliovirus (WPV) cases in Nigeria decreased from 1,122 in 2006 to six WPV type 1 (WPV1) in 2014 (1). During August 2014-July 2016, no WPV cases were detected; during August-September 2016, four cases were reported in Borno State. An insurgency in northeastern Nigeria had resulted in 468,800 children aged <5 years deprived of health services in Borno by 2016. Military activities in mid-2016 freed isolated families to travel to camps, where the four WPV1 cases were detected. Oral poliovirus vaccine (OPV) campaigns were intensified during August 2016-December 2017; since October 2016, no WPV has been detected (2). Vaccination activities in insurgent-held areas are conducted by security forces; however, 60,000 unvaccinated children remain in unreached settlements. Since 2018, circulating vaccine-derived poliovirus type 2 (cVDPV2) has emerged and spread from Nigeria to Niger and Cameroon; outbreak responses to date have not interrupted transmission. This report describes progress in Nigeria polio eradication activities during January 2018-May 2019 and updates the previous report (2). Interruption of cVDPV2 transmission in Nigeria will need increased efforts to improve campaign quality and include insurgent-held areas. Progress in surveillance and immunization activities will continue to be reviewed, potentially allowing certification of interruption of WPV transmission in Africa in 2020.

Interpersonal and community influences affecting childhood vaccination decision-making among Nigerian caregivers: Perceptions among frontline workers in Nigeria.

Although routine immunization has contributed to a substantial reduction in mortality from vaccine-preventable diseases globally, vaccine-preventable diseases are attributable for 22% of childhood deaths in Nigeria. Individual and structural level factors that influence vaccination uptake in Nigeria have been well documented. However, there is limited information about the role of interpersonal and community level factors. Frontline workers play a crucial role in delivering life-saving vaccines in Nigeria, as they are tasked with ensuring that all children are vaccinated, within the health system as well as traveling to underserved areas, where health systems are not able to reach. This qualitative study conducted focus groups to examine frontline workers' perceptions of influences affecting caregivers' vaccine-related decision-making. Community- and facility-based frontline workers (n = 47) identified village and community chiefs, as well as religious leaders as influential within the context of immunization uptake because of their trusted role within communities. Male partners and husbands were identified as also holding an enormous level of influence over childhood vaccination, and the credibility of frontline workers influenced vaccination coverage. Immunization programs should target not only caregivers but also key influencers-such as interpersonal and community sources-to make progress in reaching vaccination coverage goals.

Progress Toward Poliomyelitis Eradication - Nigeria, January-December 2017.

Nearly three decades after the World Health Assembly launched the Global Polio Eradication Initiative in 1988, four of the six World Health Organization (WHO) regions have been certified polio-free (1). Nigeria is one of three countries, including Pakistan and Afghanistan, where wild poliovirus (WPV) transmission has never been interrupted. In September 2015, after >1 year without any reported WPV cases, Nigeria was removed from WHO's list of countries with endemic WPV transmission (2); however, during August and September 2016, four type 1 WPV (WPV1) cases were reported from Borno State, a state in northeastern Nigeria experiencing a violent insurgency (3). The Nigerian government, in collaboration with partners, launched a large-scale coordinated response to the outbreak (3). This report describes progress in polio eradication activities in Nigeria during January-December 2017 and updates previous reports (3-5). No WPV cases have been reported in Nigeria since September 2016; the latest case had onset of paralysis on August 21, 2016 (3). However, polio surveillance has not been feasible in insurgent-controlled areas of Borno State. Implementation of new strategies has helped mitigate the challenges of reaching and vaccinating children living in security-compromised areas, and other strategies are planned. Despite these initiatives, however, approximately 130,000-210,000 (28%-45%) of the estimated 469,000 eligible children living in inaccessible areas in 2016 have not been vaccinated. Sustained efforts to optimize surveillance and improve immunization coverage, especially among children in inaccessible areas, are needed.

Experiences and Lessons From Polio Eradication Applied to Immunization in 10 Focus Countries of the Polio Endgame Strategic Plan.

Nine polio areas of expertise were applied to broader immunization and mother, newborn and child health goals in ten focus countries of the Polio Eradication Endgame Strategic Plan: policy & strategy development, planning, management and oversight (accountability framework), implementation & service delivery, monitoring, communications & community engagement, disease surveillance & data analysis, technical quality & capacity building, and partnerships. Although coverage improvements depend on multiple factors and increased coverage cannot be attributed to the use of polio assets alone, 6 out of the 10 focus countries improved coverage in three doses of diphtheria tetanus pertussis containing vaccine between 2013 and 2015. Government leadership, evidence-based programming, country-driven comprehensive operational annual plans, community partnership and strong accountability systems are critical for all programs and polio eradication has illustrated these can be leveraged to increase immunization coverage and equity and enhance global health security in the focus countries.

Legacy of Polio-Use of India's Social Mobilization Network for Strengthening of the Universal Immunization Program in India.

The Social Mobilization Network (SMNet) has been lauded as one of the most successsful community engagement strategies in public health for its role in polio elimination in India. The UNICEF-managed SMNet was created as a strategy to eradicate polio by engaging >7000 frontline social mobilizers to advocate for vaccination in some of the most underserved, marginalized, and at-risk communities in India. This network focused initially on generating demand for polio vaccination but later expanded its messaging to promote routine immunization and other health and sanitation interventions related to maternal and children's health. As an impact of the network's interventions, in collaboration with other eradication efforts, these high-risk pockets witnessed an increase in full routine immunization coverage. The experience of the SMNet offers lessons for health-system strengthening for social mobilization and promoting positive health behaviors for other priority health programs like the Universal Immunization Program.

Continued Endemic Wild Poliovirus Transmission in Security-Compromised Areas - Nigeria, 2016.

On August 10, 2016, 2 years after the most recent wild poliovirus (WPV) case was reported in Nigeria (in July 2014) (1), two WPV cases were reported in the northeastern state of Borno, which has been severely affected by insurgency-related insecurity since 2013. On September 9 and 26, 2016, two additional WPV cases were reported in Borno in children whose families migrated from security-compromised, inaccessible areas of the state. All four cases were WPV serotype 1 (WPV1), with genetic differences indicating prolonged undetected transmission. A large-scale emergency response plan was developed and implemented. The plan initially called for vaccination of 815,791 children during August 15-18 in five local government areas (LGAs) in the immediate vicinity of the first two WPV cases. Subsequently, the plan was expanded to regionally synchronized supplementary immunization activities (SIAs), conducted during August 27-December 6 in five Lake Chad basin countries at increased risk for national and regional WPV1 transmission (Cameroon, Central African Republic, Chad, Niger, and Nigeria). In addition, retrospective searches for missed cases of acute flaccid paralysis (AFP), enhanced environmental surveillance for polioviruses, and polio surveillance system reviews were conducted. Prolonged undetected WPV1 transmission in Borno State is a consequence of low population immunity and severe surveillance limitations associated with insurgency-related insecurity and highlights the risk for local and international WPV spread (2). Increasing polio vaccination coverage and implementing high-quality polio surveillance, especially among populations in newly secured and difficult-to-access areas in Borno and other Lake Chad basin areas are urgently needed.

Role of Social Mobilization (Network) in Polio Eradication in India.

In 2009, India contributed to over half the global cases of poliomyelitis. Many believed that India would be the last country to be polio free. India proved them wrong and was certified polio free in 2014. In January 2016, India celebrated 5 years of being polio free. One of the major reasons behind the interruption of polio transmission in the Polio endemic states of Uttar Pradesh and Bihar was the deployment of Social Mobilization Network (SMNet). A three tiered structure, the 7300 strong SMNet is now the gold standard in public health communication. It mobilizes communities by spearheading civil society participation; and works at district, block and community levels. The SMNet's social mobilization has evolved into an accelerated approach for achieving results with principles of mobilization at its core. The SMNet targets resistance to polio immunization through a multipronged approach by using local religious leaders, community influencers, interpersonal communication, counseling, mothers meetings, announcements from religious institutions and rallies. The success of the SMNet has been its ability to identify and convert resistant families into advocates for polio immunization. Deeply respected in the community, the SMNet mobilizers (98 percent of whom are women) are themselves models for gender empowerment. The SMNet model shows how mobilization techniques can be harnessed for short term and long term goals and can be replicated in other health programs to achieve the same results as were achieved for Polio.