Effectiveness of poliovirus vaccines against circulating vaccine-derived type 2 poliomyelitis in Nigeria between 2017 and 2022: a case-control study.

BACKGROUND: Between 2018 and 2022, Nigeria experienced continuous transmission of circulating vaccine-derived type 2 poliovirus (cVDPV2), with 526 cases of cVDPV2 poliomyelitis detected in total and approximately 180 million doses of monovalent type 2 oral poliovirus vaccine (mOPV2) and 450 million doses of novel type 2 oral poliovirus vaccine (nOPV2) delivered in outbreak response campaigns. Inactivated poliovirus vaccine (IPV) was introduced into routine immunisation in 2015, with a second dose added in 2021. We aimed to estimate the effectiveness of nOPV2 against cVDPV2 paralysis and compare nOPV2 effectiveness with that of mOPV2 and IPV. METHODS: In this retrospective case-control study, we used acute flaccid paralysis (AFP) surveillance data in Nigeria from Jan 1, 2017, to Dec 31, 2022, using age-matched, onset-matched, and location-matched cVDPV2-negative AFP cases as test-negative controls. We also did a parallel prospective study from March, 2021, using age-matched community controls from the same settlement as the cases. We included children born after May, 2016, younger than 60 months, for whom polio immunisation history (doses of OPV from campaigns and IPV) was reported. We estimated the per-dose effectiveness of nOPV2 against cVDPV2 paralysis using conditional logistic regression and compared nOPV2 effectiveness with that of mOPV2 and IPV. FINDINGS: In the retrospective case-control study, we identified 509 cVDPV2 poliomyelitis cases in Nigeria with case verification and paralysis onset between Jan 1, 2017, and Dec 31, 2022. Of these, 82 children were excluded for not meeting inclusion criteria, and 363 (85%) of 427 eligible cases were matched to 1303 test-negative controls. Cases reported fewer OPV and IPV doses than test-negative controls (mean number of OPV doses 5·9 [SD 4·2] in cases vs 6·7 [4·3] in controls; one or more IPV doses reported in 95 [26%] of 363 cases vs 513 [39%] of 1303 controls). We found low per-dose effectiveness of nOPV2 (12%, 95% CI -2 to 25) and mOPV2 (17%, 3 to 29), but no significant difference between the two vaccines (p=0·67). The estimated effectiveness of one IPV dose was 43% (23 to 58). In the prospective study, 181 (46%) of 392 eligible cases were matched to 1557 community controls. Using community controls, we found a high effectiveness of IPV (89%, 95% CI 83 to 93, for one dose), a low per-dose effectiveness of nOPV2 (-23%, -45 to -5) and mOPV2 (1%, -23 to 20), and no significant difference between the per-dose effectiveness of nOPV2 and mOPV2 (p=0·12). INTERPRETATION: We found no significant difference in estimated effectiveness of the two oral vaccines, supporting the recommendation that the more genetically stable nOPV2 should be preferred in cVDPV2 outbreak response. Our findings highlight the role of IPV and the necessity of strengthening routine immunisation, the primary route through which IPV is delivered. FUNDING: Bill & Melinda Gates Foundation and UK Medical Research Council.

Expanding polio surveillance reach beyond vaccination reach in Borno State, Nigeria: The contribution of community informants from insecure areas engaged to conduct polio surveillance in security compromised areas, 2018-2019.

INTRODUCTION: Borno state in north-eastern Nigeria is the epicentre of the >10 years' insurgency activities that have affected the region since 2009, resulting in the destruction of health facilities, killing of health workers, massive population displacement and lack of access to populations to provide health services. This article demonstrates how the involvement of community informants from insecure areas (CIIA) to conduct polio surveillance in security-challenged settlements of Borno state contributed to the expansion of polio surveillance reach beyond polio vaccination reach. METHOD: In each of the 19 security compromised Local Government areas (LGAs) with community informants from insecure areas, Android phones enabled with Vaccination Tracking System (VTS) technology and Open Data Kit (ODK) mobile application were provided to capture geo-coordinates as evidence (geo evidence) for polio surveillance activity conducted. These geo evidence captured were uploaded and mapped to show insecure settlements reached with polio surveillance and those yet to be reached. RESULTS: A total of 3183 security compromised settlements were reached for polio surveillance between March 2018 and October 2019 with valid geo evidence, 542 of these security-compromised settlements had not been previously reached by any other intervention for polio surveillance or polio vaccination. CONCLUSION: The capturing of geo-coordinates as a proxy indicator of polio surveillance activity conducted by informants provided significant evidence of settlements reached for sustained polio surveillance even when a case of Acute Flaccid Paralysis (AFP) had not been reported from these settlements. Using the geo evidence captured by CIIA in insecure settlements, we have demonstrated the expansion of polio surveillance reach beyond polio vaccination reach in Borno state.

Impact of Supplementary Immunization Activities using Novel Oral Polio Vaccine Type 2 during a Large outbreak of Circulating Vaccine-Derived Poliovirus in Nigeria.

BACKGROUND: Novel oral poliovirus vaccine (OPV) type 2 (nOPV2) has been made available for outbreak response under an emergency use listing authorization based on supportive clinical trial data. Since 2021 more than 350 million doses of nOPV2 were used for control of a large outbreak of circulating vaccine-derived poliovirus type 2 (cVDPV2) in Nigeria. METHODS: Using a bayesian time-series susceptible-infectious-recovered model, we evaluate the field effectiveness of nOPV2 immunization campaigns in Nigeria compared with campaigns using monovalent OPV type 2 (mOPV2). RESULTS: We found that both nOPV2 and mOPV2 campaigns were highly effective in reducing transmission of cVDPV2, on average reducing the susceptible population by 42% (95% confidence interval, 28-54%) and 38% (20-51%) per campaign, respectively, which were indistinguishable from each other in this analysis (relative effect, 1.1 [.7-1.9]). Impact was found to vary across areas and between immunization campaigns. CONCLUSIONS: These results are consistent with the comparable individual immunogenicity of nOPV2 and mOPV2 found in clinical trials but also suggest that outbreak response campaigns may have small impacts in some areas requiring more campaigns than are suggested in current outbreak response procedures.

A systematic review and meta-analysis of radon risk exposure from drinking water resources in Nigeria.

Elevated radon concentrations in drinking water pose an increased risk of cancer among nonsmokers. A Monte-Carlo Simulation was employed to assess the effective dose and cancer risk associated with radon exposure in humans, utilizing a systematic review and meta-analysis of related studies. These studies were sourced from databases including PubMed, Web of Science, Scopus, Science Direct, and Google Scholar, focusing on drinking water from Nigeria's six geopolitical zones. The random effects models revealed a 222Rn concentration in drinking water of Nigeria at 25.01, with 95% confidence intervals (CI) of 7.62 and 82.09, indicating significant heterogeneity of (I2 = 100%; p < 0.001). The probabilistic risk of effective dose revealed a best-scenario (P 5%) at Kundiga and Magiro that exceeded the World Health Organization's (WHO) recommended effective dose limit of 200 µSv/y. Conversely, the worst-case scenario (P 95%) indicated concentrations surpassing the recommended limit at Kundiga, Edbe, Magiro, Ekiti, and Abeokuta. Excess Life Cancer Risk for infants, children, and adults attributed to the ingestion and inhalation of radon from various drinking water sources exceeded the recommended values of 0.2 x 10-3 established by the International Commission on Radiological Protection (ICRP) and the United Nations Scientific Committee on the Effect of Atomic Radiation (UNSCEAR). It underscores the necessity for treating radon-polluted water, employing methos such as aeration and granular activated carbon (GAC) processes.

Potentially toxic metals in irrigation water, soil, and vegetables and their health risks using Monte Carlo models.

Food safety has become a serious global concern because of the accumulation of potentially toxic metals (PTMs) in crops cultivated on contaminated agricultural soils. Amongst these toxic elements, arsenic (As), cadmium (Cd), chromium (Cr), and lead (Pb) receive worldwide attention because of their ability to cause deleterious health effects. Thus, an assessment of these toxic metals in the soils, irrigation waters, and the most widely consumed vegetables in Nigeria; Spinach (Amaranthushybridus), and Cabbage (Brassica oleracea) was evaluated using inductively coupled plasma-optical emission spectroscopy (ICP-OES). The mean concentration (measured in mg kg-1) of the PTMs in the soils was in the sequence Cr (81.77) > Pb(19.91) > As(13.23) > Cd(3.25), exceeding the WHO recommended values in all cases. This contamination was corroborated by the pollution evaluation indices. The concentrations (measured in mg l-1) of the PTMs in the irrigation water followed a similar pattern i.e. Cr(1.87) > Pb(1.65) > As(0.85) > Cd(0.20). All the PTMs being studied, were found in the vegetables with Cr (5.37 and 5.88) having the highest concentration, followed by Pb (3.57 and 4.33), and As (1.09 and 1.67), while Cd (0.48 and 1.04) had the lowest concentration (all measured in mg kg-1) for cabbage and spinach, respectively. The concentration of the toxic metals was higher in spinach than in cabbage, which may be due to the redistribution of the greater proportion of the metals above the ground tissue, caused by the bioavailability of metals in the aqueous phase. Expectedly, the hazard index (HI),and carcinogenic risk values of spinach were higher than that of cabbage. This implies that spinach poses potentially higher health risks. Similarly, the Monte Carlo simulation results reveal that the 5th percentile, 95th percentile, and 50th percentile of the cumulative probability of cancer risks due to the consumption of these vegetables exceeds the acceptable range of 1.00E-6 and 1.00E-4. Thus, the probable risk of a cancerous effect is high, and necessary remedial actions are recommended.

Groundwater pollutants characterization by geochemometric technique and geochemical modeling in tropical savanna watershed.

Multiple interactions of geogenic and anthropogenic activities can trigger groundwater pollution in the tropical savanna watershed. These interactions and resultant contamination have been studied using applied geochemical modeling, conventional hydrochemical plots, and multivariate geochemometric methods, and the results are presented in this paper. The high alkalinity values recorded for the studied groundwater samples might emanate from the leaching of carbonate soil derived from limestone coupled with low rainfall and high temperature in the area. The principal component analysis (PCA) unveils three components with an eigenvalue > 1 and a total dataset variance of 67.37%; this implies that the temporary hardness of the groundwater and water-rock interaction with evaporite minerals (gypsum, halite, calcite, and trona) is the dominant factor affecting groundwater geochemistry. Likewise, the PCA revealed anthropogenic contamination by discharging [Formula: see text] [Formula: see text][Formula: see text] and [Formula: see text] from agricultural activities and probable sewage leakages. Hierarchical cluster analysis (HCA) also revealed three clusters; cluster I reflects the dissolution of gypsum and halite with a high elevated load of [Formula: see text] released by anthropogenic activities. However, cluster II exhibited high [Formula: see text] and [Formula: see text] loading in the groundwater from weathering of bicarbonate and sylvite minerals. Sulfate ([Formula: see text]) dominated cluster III mineralogy resulting from weathering of anhydrite. The three clusters in the Maiganga watershed indicated anhydrite, gypsum, and halite undersaturation. These results suggest that combined anthropogenic and natural processes in the study area are linked with saturation indexes that regulate the modification of groundwater quality.

Innovative strategies developed to mitigate the impact of COVID-19 pandemic on polio surveillance in Nigeria, 2020.

Introduction: following the spread of the COVID-19 pandemic to Nigeria, the Federal Government of Nigeria restricted human and vehicular movements to curb the spread of the disease. This action had a negative impact on Acute Flaccid Paralysis (AFP) surveillance, with a resultant reduction in the number of AFP cases reported. This paper describes the impact of the COVID-19 pandemic on poliovirus surveillance in Nigeria and the proactive interventions by Nigeria´s polio program to mitigate the impact of COVID-19 on polio surveillance. Methods: nine innovative strategies were implemented in all 774 Local Government Areas (LGA) of the 36 states and Federal Capital Territory (FCT) of the country. These strategies were developed by the national surveillance officers and operationalized by sub-national surveillance officers with different strategies starting at different epidemiological weeks from week 14 to 23, 2020. Many of the strategy innovations were technology-based and included: the use of mobile phones to send the AFP case definition and video by WhatsApp or by SMS, the use of state-specific toll-free numbers and Mobile Telephone Network (MTN) (mobile service provider) CallerfeelTM to community informants (CI) who were the main targets of the interventions to increase case detection and reporting. Others included the use of abridged e-surveillance integrated supportive supervision (ISS) checklists, virtual monthly DSNO meetings, and batched AFP stool specimen transportation network. Results: compared to the same period in 2019, the cumulative rate of AFP case detection and reporting had gradually declined from 39.1% in January to 16.7% before the commencement of the interventions in week 20, 2020. However, the detection and reporting increased by 57.% from week 20 to week 47 compared to the same period in 2019. This is because with COVID-19, hospital visitation dropped, and the sick remained in the communities, so the CI network was relied on to detect and report AFP cases. The cumulative proportion of AFP cases reported by community informants as of week 47 increased from 13% in 2018 to 21% in 2020. This indicates an increase of 38%. Thirty-five AFP cases were detected and reported using the MTN Caller Feel strategy, while 15 cases were reported through state-specific toll-free numbers. Conclusion: the implementation of the innovative strategies was able to mitigate the low AFP case detection and reporting observed at the initial stage of the COVID-19 pandemic. The use of technology facilitated reaching the CI network, which was more instrumental in detecting and reporting the cases.

Historical reconstruction of inaccessibility status in Local Government Areas (LGAs) of Borno and Yobe States, Nigeria, 2010-2020.

Introduction: ultimately detected in 2016, wild poliovirus (WPV) transmission continued undetected after 2011 in Northeast Nigeria Borno and Yobe States in security-compromised areas, inaccessible due to armed insurgency. Varying inaccessibility prevented children aged <5 years in these areas from polio vaccination interventions and surveillance, while massive population displacements occurred. We examined progress in access over time to provide data supporting a very low probability of undetected WPV circulation within remaining trapped populations after 2016. Methods: to assess the extent of inaccessibility in security-compromised areas, we obtained empirical historical data in 2020 on a quarterly and annual basis from relevant polio eradication staff for the period 2010-2020. The extent of access to areas for immunization by recall was compared to geospatial data from vaccinator tracking. Population estimates over time in security-compromised areas were extracted from satellite imagery. We compared the historical access data from staff with tracking and population esimates. Results: access varied during 2010-2020, with inaccessibility peaking during 2014-2016. We observed concurrent patterns between historical recalled data on inaccessibility and contemporaneous satellite imagery on population displacements, which increased confidence in the quality of recalled data. Conclusion: staff-recalled access was consistent with vaccinator tracking and satellite imagery of population displacments. Despite variability in inaccessibility over time, innovative immunization initiatives were implemented as access allowed and surveillance initiatives were initiated to search for poliovirus transmission. Along with escape and liberation of residents by the military in some geographic areas, these initiatives resulted in a massive reduction in the size of the unvaccinated population remaining resident.

Experience and findings from surveillance peer review in Nigeria, August 2017-May 2019.

Introduction: acute flaccid paralysis (AFP) surveillance is the gold standard of the Global Polio Eradication Initiative (GPEI) for detecting cases of poliomyelitis and tracking poliovirus transmission. Nigeria's AFP surveillance performance indicators are among the highest in countries of the World Health Organization (WHO) African Region. The primary AFP surveillance performance indicators are the rate of non-polio AFP among children and the proportion of timely, adequate specimen collection. The surveillance working group of the National Emergency Operations Centre assessed the quality of AFP surveillance data in some reportedly high-performing states. Methods: we conducted a retrospective review of AFP surveillance performance indicators in Nigeria for 2010-2019. We also reviewed data in reports from four groups of surveillance peer reviews and validation visits (conducted by in-country GPEI partners) during August 2017-May 2019 in 16 states with high primary AFP surveillance indicators; the validation visits reviewed clinical information and the dates of specimen collection and onset of paralysis with caretakers. Results: there were consistently increasing AFP surveillance primary performance indicators during 2010-2016, followed by declines during 2017-2019. From the data for 16 states with peer reviews conducted from August 2017-May 2019, overall concordance of reported and "true" (validated) AFP indicator data in peer review investigations was highly variable. True AFP concordance ranged from 58%-100%, and stool timeliness concordance ranged from 56%-95%. The most common clinical causes of reported AFP cases that were not true AFP were spastic paralysis, malaria, sickle cell disease, and malnutrition. All the states that participated in peer reviews developed surveillance improvement plans based on the gaps identified. Conclusion: Nigeria has highly sensitive AFP surveillance according to reported primary AFP performance indicators. The findings of peer reviews indicate that the AFP surveillance system needs to be strengthened and well-supervised to enhance data quality.

Assessment of open data kit mobile technology adoption to enhance reporting of supportive supervision conducted for oral poliovirus vaccine supplementary immunization activities in Nigeria, March 2017-February 2020.

Introduction: in Nigeria, supportive supervision of Supplementary Immunization Activities (SIA) is a quality improvement strategy for providing support to vaccination teams administering the poliovirus vaccines to children under 5 years of age. Supervision activities were initially reported in paper forms. This had significant limitations, which led to Open Data Kit (ODK) technology being adopted in March 2017. A review was conducted to assess the impact of ODK for supervision reporting in place of paper forms. Methods: issues with paper-based reporting and the benefits of ODK were recounted. We determined the average utilization of ODK per polio SIA rounds and assessed the supervision coverage over time based on the proportion of local government areas with ODK geolocation data per round. Results: a total of 17 problematic issues were identified with paper-based reporting, and ODK addressed all the issues. Open Data Kit-based supervision reports increased from 3,125 in March 2017 to 51,060 in February 2020. Average ODK submissions for national rounds increased from 84 in March 2017 to 459 in February 2020 and for sub-national rounds increased from 533 in July 2017 to 1,596 in October 2019. Supportive supervision coverage improved from 42.5% in March 2017 to 97% in February 2020. Conclusion: the use of digital technologies in public health has comparative advantages over paper forms, and the adoption of ODK for supervision reporting during polio SIAs in Nigeria experienced the advantages. The visibility and coverage of supportive supervision improved, consequentially contributing to the improved quality of polio SIAs.

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.

The role of polio emergency operations centers: perspectives for future disease control initiatives in Nigeria.

The Nigeria Polio Emergency Operations Centre (EOC) was established in October 2012 to strengthen coordination, provide strategic direction based on real-time data analysis, and manage all operational aspects of the polio eradication program. The establishment of seven state-level polio EOCs followed. With success achieved in the interruption of wild poliovirus (WPV) transmission as certified in 2020, the future direction of the polio EOC is under consideration. This paper describes the role of the polio EOC in other emergencies and perspectives on future disease control initiatives. A description of the functionality and operations of the polio EOC and a review of documentation of non-polio activities supported by the EOC was done. Key informant insights of national and state-level stakeholders were collected through an electronic questionnaire to determine their perspectives on the polio EOC's contributions and its future role in other public health interventions. The polio EOC structure is based on an incident management system with clear terms of reference and accountability and with full partner coordination. A decline in WPV1 cases was observed from 122 cases in 2012 to 0 in 2015; previously undetected transmission of WPV1 was confirmed in 2016 and all transmission was interrupted under the coordination of the EOCs at national and state levels. During 2014-2019, the polio EOC infrastructure and staff expertise were used to investigate and respond to outbreaks of Ebola, measles, yellow fever, and meningitis and to oversee maternal and neonatal tetanus elimination campaigns. The EOC structure at the national and state levels has contributed to the positive achievements in the polio eradication program in Nigeria and further in the coordination of other disease control and emergency response activities. The transition of the polio EOCs and their capacities to support other non-polio programs will contribute to harnessing the country's capacity for effective coordination of public health initiatives and disease outbreaks.

Descriptive epidemiology of poliomyelitis cases due to wild poliovirus type 1 and wild poliovirus type 3 in Nigeria, 2000-2020.

Introduction: in August 2020, the World Health Organization African Region was certified free of wild poliovirus (WPV) when Nigeria became the last African country to interrupt wild poliovirus transmission. The National Polio Emergency Operations Center instituted in 2012 to coordinate and manage Nigerian polio eradication efforts reviewed the epidemiology of WPV cases during 2000-2020 to document lessons learned. Methods: we analyzed reported WPV cases by serotype based on age, oral poliovirus vaccine immunization history, month and year of reported cases, and annual geographic distribution based on incidence rates at the Local Government Area level. The observed trends of cases were related to major events and the poliovirus vaccines used during mass vaccination campaigns within the analysis period. Results: a total of 3,579 WPV type 1 and 1,548 WPV type 3 laboratory-confirmed cases were reported with onset during 2000-2020. The highest WPV incidence rates per 100,000 population in Local Government Areas were 19.4, 12.0, and 11.3, all in 2006. Wild poliovirus cases were reported each year during 2000-2014; the endemic transmission went undetected throughout 2015 until the last cases in 2016. Ten events/milestones were highlighted, including insurgency in the northeast which led to a setback in 2016 with four cases from children previously trapped in security-compromised areas. Conclusion: Nigeria interrupted WPV transmission despite the challenges faced because of the emergency management approach, implementation of mass vaccination campaigns, the commitment of the government agencies, support from global polio partners, and special strategies deployed to conduct vaccination and surveillance in the security-compromised areas.

Implementing a robust adverse event of special interest surveillance for novel oral polio vaccine type 2 rollout, Nigeria, March-July 2021.

Introduction: novel oral poliovirus vaccine type 2 (nOPV2), designed to be more genetically stable than Sabin-strain oral poliovirus vaccine type 2 (mOPV2), is a new and key component of the Global Polio Eradication Initiative's strategy to combat outbreaks of circulating vaccine-derived poliovirus type 2 (cVDPV2). The World Health Organization´s (WHO´s) emergency use listing (EUL) requires extensive safety monitoring for Adverse Event of Special Interest (AESI) in its use. We implemented AESI active surveillance to monitor the safety of the nOPV2 in Nigeria. Methods: a cross-sectional assessment was conducted in Nigeria during March-June 2021 in 117 local government areas (LGAs) across 6 states and the Federal Capital Area with confirmed cVDPV2 transmission. We conducted active searches for nOPV2 AESI in all health facilities. Suspected events were ascertained, and vaccination and clinical data abstracted. Events were classified using WHO causality assessment algorithm. Data were analyzed using Epi info7. Results: total of 234 adverse events were reported after 21,997,300 doses of nOPV2 were administered, giving a crude reported incidence of 1 in 94,000 doses of nOPV2. Altogether, 221 of the 234 (94%) adverse events were classified. For 166 AESI ascertained to occur following a dose of nOPV2, the corrected crude incidence rate was 1 in 133,000 doses; 4 of the adverse events, were classified as consistent with casual association with nOPV2 vaccination. Conclusion: we found that nOPV2 had a low incidence of AESI following nOPV2 campaigns and no new or unexpected adverse event was reported. Safety monitoring should be sustained for early detection of signals and uncommon adverse events.

Providing information for decision-making in the Nigerian Polio Eradication Program, 2016-2020.

Nigeria made a coordinated effort to be certified by the World Health Organization's African Region for interrupting endemic transmission of wild poliovirus type-1 (WPV1) in August 2020 as a response to the resurgence of WPV1 cases in August 2016 after going two years without a case. The NEOC Data Working Group (DWG) was instrumental in providing quality and timely surveillance and campaign information for decision-making in order to interrupt WPV1 transmission and provide data toward documentation of its elimination for regional certification. The polio pre-campaign dashboard was used to assess the level of preparedness for Oral Poliovirus Vaccine (OPV) polio supplementary immunization activities (SIA) at three weeks, two weeks, one week, and three days to the start of each campaign implemented during 2016-2020. The administrative tally sheet, independent monitoring survey, and Lot Quality Assurance Sampling (LQAS) survey data collected and shared from the implementation level were analyzed by the EOC DWG to provide information by person, place, and time. Using a 90% threshold in LQAS surveys defining quality SIAs, the proportion of Local Government Areas (LGAs) in Nigeria's states in which post-SIA LQAS surveys were conducted that met this threshold were assessed over time. The highest level of preparedness attained by 3 days to a polio campaign during August 2016-February 2020 was 95% and the lowest attained was 77%. The admin, independent monitoring, and LQAS data analysis results were given to EOC working groups for assessing the performance and quality of each campaign. Twenty-twenty five percent of LGAs that failed LQAS were identified for repeat vaccination. Further, acute flaccid paralysis and environmental surveillance data and laboratory results were analyzed and shared with NEOC and partners. The government and partners used the information generated by the Data Working Group to take evidence-based action including determining the scope of the polio campaign, intensification of surveillance and routine immunization activities, and special intervention activities. On average, 12% of the 774 LGAs were identified as polio high risk LGAs for intervention using selected surveillance, routine immunization (RI), SIAs, and other relevant data sets. National Emergency Operation Centre Data Working Group provided quality and timely information that supported decision-making processes for the polio program in Nigeria. The quality and timely information enabled the NEOC to make evidence-based and timely decisions that contributed to gap identification and decision-making.

Deployment of novel oral polio vaccine type 2 under emergency use listing in Nigeria: the rollout experience.

In 2011, a dedicated consortium of experts commenced work on the development of the novel oral poliovirus vaccine type 2 (nOPV2). After careful and rigorous analysis of data to enable early, targeted use of the vaccine, World Health Organization´s (WHO´s) Strategic Advisory Group of Experts on Immunization (SAGE) reviewed data from accelerated clinical development of nOPV2 and endorsed entering assessment under WHO´s Emergency Use Listing (EUL) procedure. In November 2020, nOPV2 received an interim recommendation for use under EUL to enable rapid field availability and potential wider rollout of the vaccine. In December 2020, Nigeria initiated preparation to meet all criteria for initial use of nOPV2 in the country and the documentation process to verify meeting them. The process entailed addressing the status of meeting 25 readiness criteria in nine categories for nOPV2 use in Nigeria for response efforts to ongoing cVDPV2 outbreaks. During January-February 2021, Nigeria submitted the required documentation for all required indicators for nOPV2 initial use. In February 2021, the country obtained approval from the GPEI nOPV2 Readiness Verification Team to introduce nOPV2 and in March 2021, rolled out the novel vaccine in mass vaccination campaigns for outbreak response in Bayelsa, Delta, Niger, Sokoto and Zamfara states, and one area council in the Federal Capital Territory (FCT). The lessons learned from this rollout experience in Nigeria are being applied as the country streamlines and strengthens the nOPV2 rollout process across the remaining states.

Innovative strategies developed to mitigate the impact of COVID-19 pandemic on polio surveillance in Nigeria, 2020

Introduction: following the spread of the COVID-19 pandemic to Nigeria, the Federal Government of Nigeria restricted human and vehicular movements to curb the spread of the disease. This action had a negative impact on Acute Flaccid Paralysis (AFP) surveillance, with a resultant reduction in the number of AFP cases reported. This paper describes the impact of the COVID-19 pandemic on poliovirus surveillance in Nigeria and the proactive interventions by Nigeria´s polio program to mitigate the impact of COVID-19 on polio surveillance. Methods: nine innovative strategies were implemented in all 774 Local Government Areas (LGA) of the 36 states and Federal Capital Territory (FCT) of the country. These strategies were developed by the national surveillance officers and operationalized by sub-national surveillance officers with different strategies starting at different epidemiological weeks from week 14 to 23, 2020. Many of the strategy innovations were technology-based and included: the use of mobile phones to send the AFP case definition and video by WhatsApp or by SMS, the use of state-specific toll-free numbers and Mobile Telephone Network (MTN) (mobile service provider) CallerfeelTM to community informants (CI) who were the main targets of the interventions to increase case detection and reporting. Others included the use of abridged e-surveillance integrated supportive supervision (ISS) checklists, virtual monthly DSNO meetings, and batched AFP stool specimen transportation network. Results: compared to the same period in 2019, the cumulative rate of AFP case detection and reporting had gradually declined from 39.1% in January to 16.7% before the commencement of the interventions in week 20, 2020. However, the detection and reporting increased by 57.% from week 20 to week 47 compared to the same period in 2019. This is because with COVID-19, hospital visitation dropped, and the sick remained in the communities, so the CI network was relied on to detect and report AFP cases. The cumulative proportion of AFP cases reported by community informants as of week 47 increased from 13% in 2018 to 21% in 2020. This indicates an increase of 38%. Thirty-five AFP cases were detected and reported using the MTN Caller Feel strategy, while 15 cases were reported through state-specific toll-free numbers. Conclusion: the implementation of the innovative strategies was able to mitigate the low AFP case detection and reporting observed at the initial stage of the COVID-19 pandemic. The use of technology facilitated reaching the CI network, which was more instrumental in detecting and reporting the cases.

COVID-19 vaccine hesitancy amongst healthcare workers: An assessment of its magnitude and determinants during the initial phase of national vaccine deployment in Nigeria.

Background: While vaccination plays a critical role in the global response to the COVID-19 pandemic, vaccine rollout remains suboptimal in Nigeria and other Low- and Middle-income countries (LMICs). This study documents the level of hesitancy among health workers (HWs) during the initial COVID-19 vaccine deployment phase in Nigeria and assesses the magnitude and determinants of hesitancy across Nigeria. Methods: A cross sectional study across all States in Nigeria was conducted with over 10,000 HWs interviewed between March and April 2021. Data were cleaned and analyzed with proportions and confidence intervals of hesitancy documented and stratification by HW category. We compared the level of confidence/acceptance to be vaccinated across Nigeria and documented the sources of negative information amongst HWs who refused the vaccine. Findings: Among the 10 184 HWs interviewed, 9 369 [92% (95% CI= 91, 92)] were confident of the COVID-19 vaccines and were already vaccinated at the time of this survey. Compared to HWs who were less than 20 years old, those aged 50 - 59 years were significantly more confident of the COVID-19 vaccines and had been vaccinated (OR=3.8, 95% CI=2.3 - 6.4, p<0.001). Only 858 (8%) of the HWs interviewed reported being hesitant with 57% (479/858) having received negative information, with the commonest source of information from social media (43.4%.). Interpretation: A vast majority of HWs who were offered COVID-19 vaccines as part of the first phase of national vaccine roll out were vaccinated and reported being confident of the COVID-19 vaccines. The reported hesitancy was due mainly to safety issues, and negative information about vaccines from social media. The issues identified remain a significant risk to the success of subsequent phases of the vaccine rollout in Nigeria. Funding: None.

Conducting public health surveillance in areas of armed conflict and restricted population access: a qualitative case study of polio surveillance in conflict-affected areas of Borno State, Nigeria.

This study examined the impact of armed conflict on public health surveillance systems, the limitations of traditional surveillance in this context, and innovative strategies to overcome these limitations. A qualitative case study was conducted to examine the factors affecting the functioning of poliovirus surveillance in conflict-affected areas of Borno state, Nigeria using semi-structured interviews of a purposeful sample of participants. The main inhibitors of surveillance were inaccessibility, the destroyed health infrastructure, and the destroyed communication network. These three challenges created a situation in which the traditional polio surveillance system could not function. Three strategies to overcome these challenges were viewed by respondents as the most impactful. First, local community informants were recruited to conduct surveillance for acute flaccid paralysis in children in the inaccessible areas. Second, the informants engaged in local-level negotiation with the insurgency groups to bring children with paralysis to accessible areas for investigation and sample collection. Third, GIS technology was used to track the places reached for surveillance and vaccination and to estimate the size and location of the inaccessible population. A modified monitoring system tracked tailored indicators including the number of places reached for surveillance and the number of acute flaccid paralysis cases detected and investigated, and utilized GIS technology to map the reach of the program. The surveillance strategies used in Borno were successful in increasing surveillance sensitivity in an area of protracted conflict and inaccessibility. This approach and some of the specific strategies may be useful in other areas of armed conflict.